Answer:
The unification of Mongol tribes by Temujin, is the correct answer.
Step-by-step explanation:
The real name of Mongol leader Genghis Khan was Temujin. He united the Mongol tribes of the Mongolian plateau and conquered central Asia and China. His empire was further expanded by his descendants to far off places like Poland, Vietnam, Syria, and Korea. At its peak, the Mongol empire was spread over more than 11 hundred square miles. Although mass killings were part of Genghis khan's invasions, he also gave religious freedom to his subjects and encourages trade and commerce.