Genghis khan united the mongols and built an empire by combining a) samurai warriors ruling the clans. b) shogunates within a feudal system. c) mongol battle tactics with a belief in racial superiority. d) a superior cavalry with a confederation of tribes and clans.

The answer is D. Superior cavalry with confederation of Tribes and Clans
Before Gengis Khan took control, various Tribes and Clans in Mongol involved in civil disputes with one another
The cavalry alllow Gengis' khan army to move on top of difficult terrain with ease and give them competitive advantage in every war.

Yes, reasons why is sectionalism compromise of 1850 and secession i hope this

Aztec and hopi that was the main property