In the languages I know, verbal tense, number, gender, etc. is applied after the word stem. Is there any language where verb conjugation morphologically affects the beginning of a word and not the end of it?
Since Bantu has been mentioned, I won't mention it again, much. I'll mention Athabaskan, Ket (not Athabaskan but probably related), Semitic, Berber, Coptic, Bongo, Krongo, Nilotic, Nyulnyul, Gooniyandi, Tiwi, Lenakel, Camsá, Cayuvava, Seri, Nahuatl, Lakota. You can get more examples here. That said, if you mean "only prefixing, with no suffixing at all", then that may be hard to find. The situation in Bantu is that tense-aspect-mood-polarity and sometimes subject number are marked suffixally, and tense-aspect-mood-polarity and subject are more marked (more distinctions are made) prefixally. In Semitic, subject can be marked in part prefixally (in the imperfective), but also suffixally. Athabaskan languages are mostly prefixing, but I don't think any are completely devoid of suffixes.
The Tupi family of languages does person and number agreement with bound verbal prefixes. Major Tupian languages include Guaraní, spoken in Paraguay; Nheengatu, spoken by a minority of Amazonian Brazilians; a number of endangered native Brazilian languages, and Old Tupi which is a substrate language of Brazilian Portuguese.
Old Tupi examples follow. I'll separate the morphemes by hyphens:
- ixé a-só "I go"
- endé ere-só "You (sing.) go"
- a'é o-só "He/she/it/they go"
- îandé ia-só "We (inclusive) go"
- oré oro-só "We (exclusive) go"
- peẽ pe-só "You (pl.) go"
- ixé a-nhe’eng "I talk"
- endé ere-nhe’eng "You (sing.) talk"
- a'é o-nhe’eng "He/she/it/they talk"
- îandé ia-nhe’eng "We (inclusive) talk"
- oré oro-nhe’eng "We (exclusive) talk"
- peẽ pe-nhe’eng "You (pl.) talk"
The rest of the verbal morphology uses both bound prefixes (ta-pe-só "you may go") and suffixes (xe-só-reme "if I go"). It also features a form of noun incorporation; the direct object, or a pronoun agreeing with it, must be tacked on before the verb as follows:
- ixé a-kunumĩ-epîák I 1s-boy-see = "I see the boy"
- ixé kunumĩ a-i-epiâk I boy 1s-3s-see = "I see the boy".
Hebrew has verb inflections at the beginning, middle, and ends of verbs. For a simple example, first person simple future tense prepends an aleph at the beginning of the verb, while past tense has a suffix.
There are more complex examples -- the three letter root "fold" gets a prefix and becomes the four letter root "duplicate".
In Slavic languages, verbs have perfective/imperfective aspects, a core grammatical feature, and it's usually done via prefixing.
For example, in Russian: delat "to do", sdelat "to have done"; kormit "to feed", pokormit "to have fed"; gotovit "cook", prigotovit "to have cooked". Basically almost every verb comes in such pairs.
Here is a list of languages which have polypersonal verbal inflexions at the beginning of the verb.
In the languages I know, verbal tense, number, gender, etc. is applied after the word stem.
Importantly, it seems that those features are marked on the verb last, i.e. after everything else has already been added. Whether they get concatenated onto the beginning of the verb or at the end, seems to be dependent on something else. The languages I listed tend to be head-final; maybe that's it.
My modest knowledge of Modern Standard Arabic, MSA, which I acquired by weekly self-study after two years of classroom exposure several years ago, have taught me that prefixes do indeed alter Arabic verbs in the imperfect aspect, but not always exclusively so--the persons of some verbs attach both a prefix and a postfix; see, e.g, tathhebiina, she goes, below tehth.hebiina. 'th' is a single letter, voiced, as in 'that' Consider the verb 'to go', transliterated in 1st, 2nd, 3rd, etc., persons(p.); the prefixes show fairly clearly in front of the root, thahab ~ /THEH-heb/:
1p sg. m/f..'athhebu ('anaa = I, 1st p. sg.),
prefix: 'a ~ /'eh/; all final u are silent in lower registers; hence, colloq: 'athheb, vs. 'athhebu;//
2p sg. m....tathhebu ('anta = you, 2nd pers. sing., masc.)//
2p sg. f....tathhebiina, ('anti = you, 2p. f. sg.)//
3p sg. m....yathhebu (huu'a = he, 3p. m. sg.),pron /YETH-heb/.//
3p sg. f....tathhebu (hii'a = she, 3p. f. sg.(but see 2p.sg.m.!)//
1p pl.......nathhab (naHnu = we, 1p. pl.)//
2p pl m.....tathhabuuna ('antum = you, 2p. m. pl.)//
2p pl f.....tathhabna ('antunna = you, 2p. f. pl.)//
3p pl m.....yathhabuuna (hum = they, 3p. m. pl.)//
3p pl f.....yathhabna (hunna, = they, 3p. f. pl.)
I would be glad to edit/correct any errors the readership may find.
The perfect tense is formed by reduplication of the root and the addition of a special set of personal endings. As in athematic present stems,Thus from drs ‘see’, dadarsa ‘he saw’, dadrsuh ‘they saw’.
The vowel of the reduplication is i/u for roots containing 1/fi, a for other roots. eg, from svap ‘sleep’, susvipa, susupuh, or sru ‘hear’ : thus susruma ‘we heard’
I beleive a few other languages of Indo-European family inherit this feature.