Final answer:
During the rule of Genghis Khan's descendants, the Mongol Empire experienced significant changes, ultimately leading to its division into four separate khanates.
Step-by-step explanation:
During the reign of Genghis Khan's descendants, the Mongol Empire underwent significant changes. Under Genghis Khan's rule, the empire became more inwardly peaceful and materialistic in its tastes, while the military became a sophisticated war machine. However, after Genghis Khan's death, the empire began to divide due to conflicts and differing preferences between his descendants. The empire eventually split into four separate khanates, each governed by a different ruler. These changes marked the end of a united Mongol Empire and a single ruler who dominated the conquered territories.