Final answer:
Kublai Khan, the grandson of Genghis Khan, succeeded him and achieved several significant accomplishments. These include becoming the first foreign emperor to rule over China and attempting to reunite the four khanates into a single empire.
Step-by-step explanation:
After the death of Genghis Khan, his grandson Kublai Khan succeeded him as the ruler of the Mongol Empire. Kublai Khan accomplished several significant achievements during his reign. One of his accomplishments was becoming the first foreign emperor to rule over China. He established the Yuan dynasty and fully conquered the Song dynasty in 1279, making him the ruler over all of China. Additionally, Kublai Khan made attempts to reunite the four khanates into a single empire, although these efforts were largely unsuccessful as the empire had already started dividing.