There is a letter thorn that suffered a great loss in Old English with its size being doubled and this double sound is hidden in plain sight. I think that thorn may be related to the Bactrian sho because I feel that a “sh” sound was the closest to a th, so it stuck.

  • Could you explain it better? – Ergative Man Mar 17 '20 at 22:35
  • Why would a letter in a Northern European writing system have any thing to do with one from a Central Asian system? In what way is a palatal continuant "closest" to a labiodental one? – Colin Fine Mar 17 '20 at 22:58
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    Its ancestry is hieroglyphic and both of them eventually come from that. – Number File Mar 18 '20 at 12:13


The two letters look similar, but were used in different places (thousands of miles apart), in very different languages (Indo-Iranian vs Germanic), in different alphabets (Greek vs Runic), for completely different sounds (postalveolar vs dental).

Most notably, the first Runic inscriptions are attested from the second century CE, and the Bactrians had been using the Greek alphabet (with their extra letter sho) for centuries before that. This is strong evidence that the Bactrians couldn't have borrowed sho from the early Runic inscription-makers.

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    But Vikings did sail as far as the Caspian Sea and Iran, why couldn't Bactrians borrow the letter directly from the Viking Runes? The absence of "a letter looking like thorn or sho somewhere in between Northern Europe and Afghanistan" is not the best argument. The best proof that the two letters are unrelated is that sho was already used by Bactrians in the 2nd century AD when the two cultures could have no contact at all. I mean, the time gap is the best proof. – Yellow Sky Mar 17 '20 at 23:40
  • @YellowSky Fair point; I'll edit. – Draconis Mar 17 '20 at 23:40
  • Bactrian is Indo-Iranian, not Indo-Aryan. – fdb Mar 18 '20 at 12:47
  • Maybe the other way around: runes borrowed it from Bactrian – Number File Mar 18 '20 at 13:48
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    @NumberFile Why would they build an entire writing system of their own, then borrow a single letter into it? – Draconis Mar 18 '20 at 15:59

The Bactrian letter <ϸ> is for /ʃ/, not /θ/. It is possible that it originated in the word χϸονο "calendar year", which is probably borrowed from Greek χρόνος. In this case, <ϸ> could have started out as an elongated <ρ>.

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