The Mongol Empire emerged from the unification of nomadic tribes in the Mongolia homeland under the leadership of Genghis Khan, who was proclaimed ruler of all Mongols in 1206. The empire grew rapidly under his rule and then under his descendants, who sent invasions in every direction. The vast transcontinental empire connected the east with the west with an enforced Pax Mongolica allowing trade, technologies, commodities, and ideologies to be disseminated and exchanged across Eurasia.
The empire began to split due to wars over succession, as the grandchildren of Genghis Khan disputed whether the royal line should follow from his son and initial heir Ögedei, or one of his other sons such as Tolui, Chagatai, or Jochi. The Toluids prevailed after a bloody purge of Ögedeid and Chagataid factions, but disputes continued even among the descendants of Tolui. After Möngke Khan died, rival kurultai councils simultaneously elected different successors, the brothers Ariq Böke and Kublai Khan, who then not only fought each other in the Toluid Civil War, but also dealt with challenges from descendants of other sons of Genghis. Kublai successfully took power, but civil war ensued as Kublai sought unsuccessfully to regain control of the Chagatayid and Ögedeid families.
Mongol invasion of Baghdad
The Battle of Ain Jalut in 1260 marked the high-water point of the Mongol conquests and was the first time a Mongol advance had ever been beaten back in direct combat on the battlefield. Though the Mongols launched many more invasions into the Levant, briefly occupying it and raiding as far as Gaza after a decisive victory at the Battle of Wadi al-Khazandar in 1299, they withdrew due to various geopolitical factors.
By the time of Kublai's death in 1294, the Mongol Empire had fractured into four separate khanates or empires, each pursuing its own separate interests and objectives: the Golden Horde khanate in the northwest; the Chagatai Khanate in the middle; the Ilkhanate in the southwest; and the Yuan dynasty in the east based in modern-day Beijing In 1304, the three western khanates briefly accepted the nominal suzerainty of the Yuan dynasty, but it was later overthrown by the Han Chinese Ming dynasty in 1368. The Genghisid rulers of the Yuan retreated to the Mongolia homeland and continued to rule the Northern Yuan dynasty, while the Golden Horde and the Chagatai Khanate lasted in one form or another for some additional centuries after the fall of the Yuan dynasty and the Ilkhanate.
(source)