 Before the end of the 4th Century BCE, the Yuezhi and Wusun were located in areas that were later part of the Chinese provinces of Gansu and Xinjiang.There was substantial interaction between the Yuezhi, the Wusun and a neighbouring people, the Xiongnu, whom many scholars have suggested were precursors of the Huns.In about 200 BCE, the Xiongnu leader Modu Chanyu – a vassal of the Yuezhi – rebelled, attacked the Yuezhi, and subjugated several other peoples.