With a POD in the rise of the Yuan dynasty, make at least 10% of the Central Asian population Chinese. (They do not need to have been taken over by a Chinese dynasty.) Bonus if they become Chinese majority.
A reason why I believe this possible is partly because of the Silk(and the general trans-Eurasian) Trade route and further because of the possible Chinese interests in controlling that route.
Well, it is impossible exactly since the rise of the Yuan dynasty.
You see that's the time when the Mongol World Empire finally disintegrated. The Yuan emperors kept the title of the Universal Khaan and for some periods they were even acknowledged by other Mongol Khanates but it was very formal recognition, the World Empire was no more.
So by that time the Central Asia was mostly controlled by Chagatai Ulus, Juchi Ulus (the Golden Horde) and some parts by Hulaguid Il-Khans.
Why would the Yuan move their Chinese population to the Central Asia which was controlled by other Khanates sometimes openly hostile to the Yuan?
Well, they might have presented some Chinese population to the Persian Il-Khans as they were of the same Tolui House as the Yuan and were in friendly relations, but for the most part these Toluid Khanates did not have direct access to each other through land because of the constant warfare in this part of Asia.
So your only chance to move the Chinese population to the Central Asia and settle them there is
before Yuan, while the World Mongol Empire was functioning.
But unlike Assyrians, Babylonians and some others the Mongols were not too enthusiastic about moving their conquered peoples across their Empire and resettling them in the new places. What for? Actually why this fuss?
You'd have hard time trying to explain Chengizz Khan or his immediate successors the necessity to move the Chinese or some other peoples somewhere. "What? We need to punish them? And you suggest moving them to the Central Asia? I have better solution: Let's slaughter one more million! That'll teach these bastards good manners!"
So, if you want to make the Central Asia Chinese, don't look at the Mongols.
If they are good at something that's depopulating, genocide, something like that.