Explain ONE way in which, as Grousset asserts in the passage, the interactions between Central Asian nomads and established Asian civilizations resulted in the “conquered . . . vanquish[ing] their conquerors.”

One way to explain the passage, the "conquered...vanquish(ing) their conquerors," was the fact that Central Asian's nomadic people often conquered the civilized places. Their devastating techniques allowed them to  defeat their conquerors.

Explanation:

Central Asia's climate and geography resulted to "nomads" who were constantly looking for favorable places which they can use for agriculture. In order to to this, they needed to launch several campaigns of conquest to the already established Asian civilizations. This led to a widespread conflict in the area. A great example of this is the "Mongol Conquest" in Eurasia.

So, this explains the answer.

2686-2181 bce-- "egyptian civilization developed along the nile river in large part because the river’s annual flooding ensured reliable, rich soil for growing crops."

1069-664 bce-- "ancient egyptians developed wide-reaching trade networks along the nile, in the red sea, and in the near east."