Genghis Khan (1162-1227) was the founder of the Mongol Empire, the largest contiguous land empire in history. He is often considered one of the greatest military commanders of all time, and his empire stretched from Central Asia to Eastern Europe and China. However, Genghis Khan was also a ruthless conqueror who committed numerous atrocities.

One of the most infamous atrocities committed by Genghis Khan was the sack of Merv, a city in Central Asia. In 1221, the Mongols besieged Merv for 18 days before finally taking the city. In the aftermath of the conquest, the Mongols massacred the entire population of Merv, estimated to be between 700,000 and 1,000,000 people. Another was the destruction of Baghdad, the capital of the Abbasid Caliphate. In 1258, the Mongols under Genghis Khan's grandson, Hulagu Khan, sacked Baghdad and massacred its inhabitants. The destruction of Baghdad is considered one of the greatest cultural disasters in history.

Genghis Khan also committed atrocities against his own people. In 1206, he ordered the execution of his brother, Khasar, for refusing to participate in a military campaign. In 1211, he ordered the execution of his wife, Börte, after she was captured by the Tatars. And in 1222, he ordered the execution of his son, Jochi, for plotting to overthrow him.

There is still debate about the extent of his cruelty. Some historians argue that he was a ruthless conqueror who was willing to do whatever it took to achieve his goals. Others argue that he was a complex figure who was both a great leader and a brutal tyrant.

Whatever the case may be, there is no doubt that Genghis Khan was a man of great power and influence. His empire left a lasting legacy on the world, both in terms of its size and its brutality.