I was talking with 俊呈 and he was explaining the character “韻” and mentioned its similarity to the Turkic “ün”. The character is pronounced “yùn” in Mandarin and “ūn” in Hokkien (俊呈 speaks both). In Hakka it is “yūn”. It is interesting to note that although the Cantonese cognate “wán”, appears unusual, it is apparently quite regular, with almost all Mandarin “yun”s being cognate to Cantonese “wan”s.
The radical behind the character is “音”, whose meanings are very close to those of “韻”, and such minor distinctions seem unlikely to have existed in the proto-language. What I’m implying, naturally, is that “韻” is some manner of Turkic loanword in Chinese. Of course it’s also possible that “ün” is a Chinese loanword in Turkic. Nişanyan is quite certain of the Turkicness of the word, and this word isn’t in lists of Turkic loanwords in Chinese such as 漢語外來詞詞典, which lists “蹋” as being from Turkic (through a fascinating semantic shift, “mountain” to “tread”):
But I still like to imagine this word is evidence of Sino-Turkic language contact. It certainly is easy enough to remember them together, what with the radical of “韻” (“音”) being used for “vowel” and the Tuvan for “vowel” being “ажык үн” (ajık ün).