Japanese and Korean have strikingly similar grammars but whether they are related or not is an open question.

Both languages have a particle to mark the grammatical subject of a sentence and in fact it is pronounced the same (within the phonetics of each language), that being "ga" (Japanese "が", Korean "가").

Is there evidence for or against these particles being genetically related, or related via borrowing, or any other kind of influence? Or is it believed the similarity is in fact purely coincidental? What is known of the etymology of each particle?

(The Korean particle actually has two forms, the one being discussed is used after vowels and "이" (i) is used after consonants, the latter has no obvious similarity to a Japanese particle I am aware of but this may or may not be otherwise relevant.)

  • Not a relevant, but somewhat related answer: Japanese Buddhist kunten*(訓点, gloss) texts from 8~9th centuries use postnomial *-i markers, and it is a loanword from Korean then-ergative marker -i, which had been evolved into the subject marker -i. yukoyanagida.com/wp/wp-content/uploads/JK212012.pdf
    – puzzlet
    Oct 15, 2012 at 18:58
  • Aren't the Korean subject particles postpositions? Oct 8, 2013 at 23:00
  • They certainly behave like postpositions but since they indicate grammatical role rather than a physical/semantic relationship I would assume there are analyses or traditions that call them particles, others that call them postpositions, and possibly others that have a special category for them. Oct 9, 2013 at 5:33
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    @puzzlet, I've read that the Old Japanese particle い (i) is an inheritance from a prehistoric proto stage, and that fusion with this may be what causes an apparent ablaut in certain nouns that have different vowel values as standalones as opposed to when used in compounds. Things like sake ("alcoholic beverage") appearing as saka- in sakaya ("liquor store"). Mar 31, 2020 at 3:34

7 Answers 7


According to 'A history of the Korean language' (p 271) the Korean subject particle ka is a recent development in that language, not being attested at all until the sixteenth century, and probably not in common use until the 18th century and thereafter. This means we can rule out the possibility that it is cognate with the Japanese ga (ie they are not similar because they are both inherited from some ancestor to the two languages).

Two other possibilities are coincidence or borrowing. Given that there is no known etymological explanation of the development of Korean ka that would show it to be a coincidence, or that would even provide any origin, the rapid development of this particle in Korean suggests it is a borrowing from Japanese.

It's worth noting that it has been proposed that the Japanese postposition -i was originally borrowed from Korean, perhaps by the 9th century.

  • Is it really incorrect to use the term cognate for words with a borrowing in their history? This seems counterintuitive to me. I might ask a new question about it. Oct 9, 2013 at 4:48
  • Words are cognate if they descend from a common ancestor. It's like a blood relationship (which is where the word comes from). It can happen that a borrowing is cognate, eg 'chief' and 'chef' (borrowed from French) in English. Oct 9, 2013 at 7:15
  • (got distracted, here's the rest): ...but in my view it would still be described as a borrowing as this would be its role in historical reconstruction. Oct 9, 2013 at 7:23
  • Also I don't know this Japanese -i particle/postposition and suffered from TL;DR with the linked paper. Does it still exist or did it change form in Japanese? Oct 9, 2013 at 7:23
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    -i was only found in a very limited distribution. Vovin (2005) reports that it is found almost exclusively in the prose texts of Western Old Japanese (spoken around modern Kyoto, ca. 700-800 CE) (Vovin 2005: 112). Additionally, there is only one attestation in Eastern Old Japanese (spoken around modern Tokyo, in the same time period as WOJ) (Vovin 2005: 112).
    – limetom
    Oct 9, 2013 at 9:22

The Japanese case marker =ga (a post-clitic), was not originally a subject marker. We can easily see this in the Ryūkyūan languages, related to Japanese, as well as historically attested forms. It's important to keep in mind that standard Japanese is actually fairly innovative when compared to other Japonic languages, both historical and modern.

Originally, =ga was a possessive case marker which happened to also have a usage as marking subjects (but only animate subjects; inanimate subjects used the genitive case marker =no) (Vovin 2005: 118). Compare this Western Old Japanese form:

  • wa=Nka kəkərə |1s-POSS heart| 'My heart' (Kojiki Kayou 3)

And this Okinawan form:

  • ari=ga guusan |3s-POSS cane| 'his/her cane' (Uchima and Nohara 2006: 66)

The primary function of Korean =ka, to the best of my knowledge, has only ever been marking subjects. Not so with Japanese =ga, so not only are we only looking at a phonetic similarity (I doubt you'll find recurrent sound correspondences here--the Proto-Japonic form was prenasalized voiced *=ŋga), but also an anachronistic similarity in meaning between modern standard Korean and modern standard Japanese.

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    Of course as pointed out in Gaston's answer Korean =ka is also a recent innovation (C16) so "only ever been ..." has a limit here. Do we have an estimated time for the standard Japanese innovation? If it's later than the Korean innovation it would strengthen the coincidence hypotheses but if earlier the influence hypothesis would be more difficult to rule out. Oct 9, 2013 at 10:53
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    Sorry, I wasn't clear. I meant that standard Japanese is often innovative in general when compared to the rest of the Japonic languages. As for when ga started to be used as a subject marker, as all modern Japonic languages have not only the possessor-marking usage, but also the subject-marking usage--as do the attested pre-modern forms of Japanese and Okinawan--we can safely date the innovation to Proto-Japonic, so sometime before the 8th century CE.
    – limetom
    Oct 9, 2013 at 11:04
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    Quick note: ga was only used in older Japanese to mark the subject of non-finite clauses, and as such was acting as a true genitive. Later, the finite verbal conjugations were lost and replaced wholesale with the non-finite conjugations, which I assume is when ga came to be used with finite clauses. It then lost its use as a general genitive, which is when no (the surviving genitive) replaced it in marking the subject (i.e. possessor) of non-finite verbals. Oct 10, 2013 at 5:13
  • @JustinOlbrantz Good catch, though while the usage is certainly infrequent in Old Japanese, Vovin (2005), at least, has several uncontroversial examples from both Western and Eastern Old Japanese. From Fudoki Kayou 6: wa=Nka wep-yi-n-i-ky-em-u |1=POSS get.drunk-INF-PERF-INF-PST/FIN-TENT-FIN| 'I got drunk.'
    – limetom
    Oct 10, 2013 at 6:18

Japanese is considered a Japonic Language together with Ryukyuan, and the Japonic languages are not widely accepted to be related to any other language family. There have been, however, many different proposals, including a relationship to Altaic, Indo-European (!), and yes, Korean. However, all of these proposals have been heavily disputed, and none of them are considered to be proven.

Even if Japanese is related to Korean, it's probably coincidence that these particular particles are related. The time depth for the supposed ancestor of Japanese and Korean would be so great that we wouldn't expect anything to have survived unchanged, and so two identical particles in both languages are probably the same due to coincidence.

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    I think the more important point is the second one: even if the two are related, it's unlikely that the particle would have remained unchanged for so long in both languages. Sep 14, 2011 at 2:42
  • Yes I chose a pretty generous wording with "open question" on purpose. I think assumptions and probablies are easy though which is why I asked for some etymological history to back up the coincidence theory and override the later influence possibility as well as the ancient relatives theory. Sep 14, 2011 at 7:46
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    @JSBangs: Saying it's a coincidence also means that it's not a sprachbund effect. Do you mean to rule out that possibility? Sep 21, 2011 at 20:26
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    To be clear, Ryukyuan is not a single language, but at least 5 languages: Amami, Okinawan, Miyako, Yaeyama, and Yonaguni. See Thorpe (1983), Serafim (2008), Pellard (2009), and Shimoji and Pellard (2011), among others whose estimates range from at least a dozen (Thorpe) to just 4 (Serafim, who merges Amami and Okinawan, which are likely a dialect chain).
    – limetom
    Oct 9, 2013 at 9:59

I'm going to suggest that any similarities would be due to borrowing, as Japanese have occupied Korea off and on for at least 1600 years {1}. There has been a lot of borrowing between Chinese, Japanese and Korean; mostly from Chinese to Japanese and Korean.

1 - Books like Sources of Japanese Tradition (and the equivalent for other nations) reference historical documents to describe how the political and social structures of the countries developed. Some of the earliest Chinese documents mentioning what we now call Japan mention that they ruled areas of what we now call Korea in the 600s and 800s.

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    I think to say 1600 years is misleading as they only occupied for a very short period of time measured in decades. The Chinese occupied Tibet for centuries yet Tibetan grammar did not change even though they are in the same language tree.
    – user719
    Jan 30, 2012 at 6:27
  • I personally would suspect linguistic influences to be more likely under general cultural influence and cross-pollination than under hostile occupation, but my hunch could be wrong. As for Chinese and Tibetan can you actually show this to be the case or is it an assumption too? Oct 9, 2013 at 4:53
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    @hippietrail Re this issue, English borrowed pronouns from Old Norse under an occupation (of decades). Oct 9, 2013 at 7:18
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    Yes very true! Even words regarded as "core" such as them. Oct 9, 2013 at 7:32
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    Japan has occupied Korea for 35 years, in total (during 1910 - 1945 A.D.) They have never occupied the Korean peninsula other than in that period. Can you please cite the exact source for that claim?
    – MujjinGun
    Aug 8, 2016 at 8:37

First, I am going to address Tangurena's answer (I don't have enough reputation to add a comment). Your claim of Japan occupying Korea for 1600 years is very misleading to say the least. Japan occupied Korea during 1910 - 1945. It is a such a shame to Koreans that they call it as 경술국치 (pronounced as Kyung-Sool-Gook-Chi), meaning national shame in the year of Kyung-Sool. Here's a wikipedia article about the treaty that took place: Japan–Korea Treaty of 1910.

Only other time that Japan invaded Korea as a country was after Toyotomi Hideyoshi united Japan (much thanks to Oda Nobunaga) and invaded Korea from 1592 - 1598. At one point they even took over the capital but Korean king at the time fled to northern part of the country, and the legendary admiral Yi Sun-sin defeated & sank numerous Japanese ships to force them to retreat back to Japan. After Toyotomi Hideyoshi died, eventually all of the Japanese troops fled back to Japan. Japanese invasions of Korea (1592–98).

One can even argue that some kingdoms (like Baekje) in Korea ruled Japanese provinces in the ancient times and did in fact influence languages and some of the cultures. Also they served as a gateway for Japan to obtain Chinese goods/cultures/ etc.

For outsiders, a good way to visualize the relationships between Korea, Japan and China might be that of France, England, and Rome. Given that relationship, it is easy to make connections for both Japanese and Korean languages to Chinese and there are definitely few features (such as writing systems for both countries have been borrowing from Chinese for much of their history as well as many words having roots originating from Chinese language).

So my "open" answer to the question of the thread is that, yes, there are definitely some influences between these two countries - both affecting each other. But keep in mind that these two are separated by sea so it is different than some of the European countries who shares borders with other countries where language can easily be influenced by each other.

Also Korea is made up of 70 ~ 80% mountainous terrain which affects the "sharing" of the language. So the caveat is that each region developed their own features while the sharing and influencing were going on.

  • This is all true and interesting, and it's often annoying that new users can't post comments. But since it doesn't include an answer to the question the moderators will surely delete your post as "not an answer" just so you know. Oct 9, 2013 at 4:46

As a Japanese-American I've put a lot of thought and reading into this. The short answer is, as others have written, it is not proven either way -- however the evidence is mounting recently in favor of a relationship. There was a time when a relationship between Korean and Japanese was thought to be likely, then linguists moved away from the hypothesis and it was considered mostly debunked, but more recently it's gained traction again with the advent of new computational linguistics evidence. One of the most prominent early proponents of a linkage is the linguist Alexander Vovin, but he later rejected the hypothesis and now believes the languages have independent origins. However, I'd say one of the most impressive new researchers in the area, Martine Robbeets of the Max Planck Institute, and her research group, have done remarkable work tying together genetic, archeological, linguistic, and computational models with compelling evidence of a genetic link between the languages.

Note that it is important when reading papers on this topic to note the dates -- every researcher in this area has steadily evolved their views on it, and the most recent papers will be the most reliable indicators of their current opinions.

Here is an interview with Robbeets where she outlines some of her groups' research on Japanese and related languages:


What I find particularly impressive about their research is they were able to use computational models to reconstruct past versions of languages and using that approach they conclude that Japonic and Koreanic had a shared ancestor, but more importantly they also were able to make a prediction that the original homeland of the shared ancestor of not only Japonic and Koreanic, but Mongolic and a number of other language groups would have been millet farmers living in a specific valley in Inner Mongolia 10,000 years BP -- and sure enough, archeological evidence shows millet farming origination in precisely that valley at precisely that point in time. An extremely impressive cross-disciplinary corroboration of their results.

Despite these varying views, however, it's well-accepted that proto-Japonic speakers once lived on the Korean peninsula -- this is accepted by both Vovin and Robbeets and there is considerable evidence for it. Japonic toponyms have been found in phonetic accounts of words used on the peninsula during the Three Kingdoms period. There is some discussion of this here:


but there are many other references.

Furthermore, another computational linguistics analysis of Japonic dialects (including Ryukyuan) concludes that they all diverged from a common ancestor approximately 2,200 years ago, which corresponds approximately to the archeological record of the largest number of bulk of the Yayoi migration to the island of Kyushu. Here's a news story covering this study, from there you can find the original paper:


This pretty much excludes the hypothesis the Japanese language evolved on the islands -- it was clearly imported by the Yayoi, and the other evidence ties this in -- proto-Japonic speakers once lived in Korea and came from there.

However, there is the problem that the core vocabulary of Korean and Japanese do not sound similar, including base words such as counting words and so on. There are very few obvious cognates except for words known to have been imported from China. For this reason most linguists still believe the languages are related only via sprachbund. I believe, however, that Robbeets' team is correct and this conventional view is not correct. Robbeets has done remarkable work showing strong evidence of their genetic relationship, but I would like to add another argument in favor of her conclusions.

I would posit two things -- the subject - object - verb word order plus the use of particles, adding in the very unusual use of wa/ga in Japanese or eun-neun/ga-i in Korean, is an extremely rare grammar in the world. There are many languages with subject-object-verb word order but almost no languages with all of these features put together. For this reason it is exceptionally unlikely that if the two languages converged by sprachbund that the original versions of either languages had a similar grammar. There just aren't many languages with such a grammar anywhere on the planet. In particular, even very subtle features such as the use of the topic and subject markers I noted above are pretty much identical in the two languages, yet this is also an incredibly unusual grammatical construct and it is furthermore extremely difficult to explain even for a native speaker. The fact that this grammatical construct exists in both languages and is pretty much identically used, down to subtle details, means the sprachbund, if it occurred, was so deep that it managed to transfer not only the overall grammatical structure but some of the most tricky and idiosyncratic details of usage.

Because this grammar is so unusual, I would posit that if they converged due to sprachbund, whatever the original grammars of these languages were, they would almost certainly have been quite different to begin with.

This in itself does not exclude the possibility of sprachbund -- however I think there is one other fact which ironically has been used to show the languages must not be genetically related, and that is the fact that there are very few if any clear cognates between the core vocabularies of either language. Here's the fundamental problem: if these two protolanguages, proto-Japonic and proto-Koreanic, started out with different grammar and converged through close interaction over a long enough period that they came to have nearly identical grammar -- why AREN'T there more cognates? With such a presumably close relationship, one would except a very large number of borrowed words in one or the other direction. Yet there's very little evidence of this at all.

One thing that is well-known in linguistics is that vocabulary changes more quickly than grammar. Grammar tends to be stable; vocabulary is fungible. Yet here we are expected to believe that these two languages converged to an extremely unusual, nearly unique grammar, without having also borrowed nearly any vocabulary at all in either direction? To my mind, this on its face makes the sprachbund hypothesis exceptionally unlikely.

The archeological evidence also doesn't really support this hypothesis. It's now known that the majority of Yayoi migration to Kyushu occurred sometime between 800 BCE and 300 BCE (it was once thought the Yayoi didn't arrive until 300 BCE but there are now known archeological records of earlier arrivals hundreds of years before). We also now believe this corresponds to the time when proto-Japonic was likely most spoken on the Korean peninsula. However, archeological evidence also shows proto-Koreanic speakers arrived on the Korean peninsula around 300 BCE. It is very likely the reason for the Japonic toponyms is the two groups overlapped and it is also very likely many ancestors of modern Koreans are descended from these proto-Japonic speakers. But the time period of overlap between proto-Japonic and proto-Koreanic was quite recent -- sometime from 300BCE to perhaps the early Three Kingdoms period. Note that an alternative hypothesis that the sprachbund may have occurred when proto-Japonic speakers lived further north, perhaps in an earlier time, seems to be excluded by the fact that the Japonic toponyms only seem to be attested in the southern part of the peninsula.

If the proposed sprachbund occurred during this overlap it's hard to explain the fact that there is little evidence of shared vocabulary from that sprachbund which is relatively recent in linguistics terms. Also, many Yayoi had already migrated to Japan before the Koreanic speakers even arrived in Korea -- yet there's no trace of whatever language they may have spoken -- the computational evidence is modern Japanese diverged from a single ancestor around the time of the Yayoi migration, with a founder effect. If Japonic had somehow evolved during this period of overlap and changed its grammar radically, it's hard to understand why there's no evidence of this and in fact it appears the modern Japonic language family came from a bottleneck event and a single ancestor founder effect at that time.

All of this evidence is far more consistent with the Robbeets proposal. In her team's account, Koreanic and Japonic speakers were once one group, but they split apart for a couple thousand years give or take, and re-encountered each other again in large numbers later, during the overlap period I mention above. During the period of separation the vocabularies diverged but the grammar remained consistent. Furthermore, Robbeets and her collaborators believe the proto-Japonic speakers encountered Austronesian speakers while living on the Liaoning peninsula, where they learned rice agriculture and may have imported new vocabulary. Since vocabulary tends to change much more rapidly than grammar, this would be consistent with what we observe: divergent vocabulary but shared grammar.

A recent (May 2020) whole-genome genetic study concludes that Koreans and Japanese branched off the same genetic root and are by far the most closely-related genetically to each other than to any other ethnic groups in East Asia:


The key graph from this paper showing their conclusions:


This is further evidence of the close genetic relationship between the two groups, which is also strongly consistent with Robbeets' hypothesis.

Finally, I'm going to point to Alexander Takenobu-Francis-Ratte's thesis in which he outlines a proposed set of patterns to explain how the vocabulary of Japonic and Koreanic may have diverged in a consistent way over the centuries and he reconstructs a core set of cognates from this of around 300 words. Vovin has strongly objected to his paper but I nevertheless leave it here as additional interesting work to add to this topic:


He is currently a linguist teaching at Furman University.

  • I recommend to stop blurring the concept of Japanese dialects and Japonic languages. The Ryukyuan languages are more conservative than Japanese, which like English or French, stands out among its family as being the most innovative/different/atypical. The grammar and particles of Ryukyuan languages can be different to Japanese but similar to each other in interesting ways. I would also recommend learning what you can about the Japanese Hachijo dialect and Korean Jeju dialects, as spoken by older/previous generations. It's a good ten years since I was actively interested in this stuff though. Aug 5, 2020 at 9:20
  • The Japanese dialects study I referenced above included Ryukyuan as part of the computational analysis, so it was intended to cover all known Japonic languages, including Ryukyuan, not only the Japanese dialects on the main islands. Even including Ryukyuan, the study concluded there was a bottleneck founder effect relatively recently, just over 2000 years ago, for the entire Japonic language family, which excludes the possibility that the Jomon peoples spoke Japonic and pretty much confirms the hypothesis that the Yayoi spoke some version of proto-Japonic. Aug 5, 2020 at 11:01

I speak Korean and am learning Japanese. Through those endeavors I have noticed a tremendous amount of overlap between the two languages--the kind of overlap that can't be coincidental in general. For this reason until proven otherwise I would start by assuming any overlap is the result of a shared history and even a shared geography (Japan was connected to Korea roughly 500 generations ago during the last ice age).

The second and direct answer to your question is Japanese and Koreans both use ~ga as subject markers but use them differently. It's too complicated to go into here but you can find guides about their usage like http://jlptbootcamp.com/2012/10/jlpt-n5-grammar-japanese-particle-ga/

Does that mean -ga was used similarly a number of generations ago and the usage is related? Knowing nothing more it's hard to say definitively. But you should also know that in general Japanese and Koreans use subject and object particles in identical manners and a few prepositions even overlap in meaning and pronunciation. Given all that and the 16th century onward usage in Korea, I also lean heavily toward borrowing rather than a cognate or coincidence to explain the overlap.

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    What about the tremendous amount of absent overlap of vocabulary other than what's borrowed from Chinese? That kind of non-overlap can be coincidence?? Now you need to do some proving. Nov 28, 2016 at 13:31
  • According to the Automated Similarity Judgment Program, it is more likely that the Japanese and Ainu languages are related to the Austroasiatic language family. Feb 26, 2018 at 0:39

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