Specifically, the earliest of the Tarim Basin mummies, including that of the "Beauty of Loulan" can be dated to c. 2000 BC.
The earliest evidence of horse domestication took place c. 4500 BC on the Pontic-Caspian steppe.
The evidence of cultural drift in central Asia at this period was from west to east.
The Old Chinese words for wheels, wheelspokes, axles, and chariots, have Indo-European etymologies.
The spoked wheel and the chariot did not appear in China until about 1500 BC.
The names Qilian and Kunlun in Chinese for certain mountains are derived from IE Tocharian and mean "holy, heavenly", implying a Tocharian presence in these mountainous regions.
The Bronze Age in the Tarim began by about 2000 BC.
The Bronze Age in original China didn't begin until about 1500 BC.