(Just to reiterate: none of this is my own, this is a summary of Alexander Vovin's 2002 "Did the Xiongnu Speak a Yeniseian Language?")
One sentence of this forgotten and mystery-shrouded Jie tongue survives, that may hold the key to unlocking the riddle. A Buddhist monk was good enough to write down a single sentence in the Jie language!
秀支 替戾剛 僕谷 劬禿當
Xiu4 zhi1 ti4 li4 gang1, pu2 gu3 qu1 tu1 dang1
Sadly, the IPA was not invented yet, so he had to use Chinese characters. So, in order to see how this sentence was actually pronounced, we first need to take off our Standard Modern Chinese goggles and switch over to Early Middle Chinese, which is like Cantonese beaten over the head with Wu:
su-ke ti-re-kang, bok-kok ko-tok-tang.
Another thing the helpful monk did was give us a gloss. Here it is:
“Armies (have gone/will go) go out and (have captured/will capture) Bokkok”
Whatever Bokkok did, I’d hate to be him.
Linguists have been having a great time with this one. Originally pretty much everyone assumed the language would be Turkic, and did some pretty incredible mental gymnastics to make it Turkic. Some linguists, for example, conveniently left out the “Reconstructing Ancient Chinese” part, while others did things like phonetic or grammatical tweaking. This is the kind of stuff I used to do in college when I was writing a paper two hours before it was due (““tirekang” means nothing in Old Turkic, but “tashyqyng” does! Close enough. Now, where did I put my beer?”) The reality is that the sentence doesn’t “fit” with Turkic, and attempting to make it fit is betrayal of the scientific method.
But interestingly, what does seem to fit is none other than Proto-Yeniseian, the ancestor of my favorite language, Ket. What’s even more interesting is that “Jie” is pronounced just like “Ket” in Early Middle Chinese. In Cantonese, “Jie” is still pronounced “kit”. In Japanese it’s “ketsu”. Proto-Yeniseian was spoken 2000 years ago, so it’s not completely farfetched that some Yeniseian-speaking badasses might have been lured down into what is now China.