Short answers, pulled from the story.
Temüjin was born into a world of brutal survival and became the son of a minor chieftain who was poisoned by Tatars when the boy was only nine years old. His family was abandoned by their own tribe on the frozen steppe, leaving his mother Hö'elün to raise him and his siblings by gathering wild plants and hunting small game.
Genghis Khan died on the 18th of August 1227 leaving an empire that stretched from the Pacific Ocean to the Caspian Sea. This territory was twice the size of the Roman Empire or the Muslim Caliphate at their height.
The Mongol Empire fractured into autonomous khanates after the death of Möngke Khan on the 11th of August 1259 which triggered a civil war. The war ended with Ariqboke surrendering to Kublai at Shangdu on the 21st of August 1264 and the empire splitting into the Yuan dynasty and three western khanates.
The plague known as the Black Death started in the Mongol dominions and spread to Europe in the 1340s. The total number of deaths worldwide from the pandemic is estimated at 75 million with up to 50 million deaths in Europe alone.
The Han Chinese overthrew the Yuan dynasty in 1368 launching their own Ming dynasty and pursuing a policy of economic isolationism. The Mongols fled to their heartland in Mongolia and the empire disintegrated into smaller khanates that declined steadily in power over four centuries.