Answer:
Hittite civilization ------- Historians know very little about this civilization.
Assyrian civilization ------ Conflict between the king and his brother could be the cause for its downfall.
Babylonian civilization ------ They took over the Sumerian civilization.
Explanation:
Conflict between the king of Assyria and his brother over the control of the throne made the empire weaker and responsible for the fall of Assyrian civilization
. Babylonian civilization ended the rule of Sumerian in a battle and finally ended the Sumerian civilization. Historians know very little about Hittite civilization due to lack of the evidences in the region where they lived.
