This policy was in line with Emperor Wu 's expansionary goals of challenging the nomadic Xiongnu Confederation while colonising the Hexi Corridor .
What is now Xinjiang of Central Asia , Northern Vietnam , Yunnan , and North Korea .
This policy was in line with Emperor Wu 's expansionary goals of challenging the nomadic Xiongnu Confederation while colonising the Hexi Corridor and what is now Xinjiang of Central Asia , Northern Vietnam , Yunnan , and North Korea .