What was the name of the famous mongol ruler who finally defeated the song dynasty and saw the complete conquest of china a. ibn battutah b. tang taizhong c. genghis khan d. kublai khan

The answer is D, Kublai Khan.

Ongoing civil wars western roman empire finally collapsed476 c.e. romulus, the last of theroman  emperors in  the west, was overthrown by the germanic leader odoacer, who became the first barbarian to rule in rome. the order that the  roman empire  had brought towestern  europe for 1000 years was no more.