The Mongol Empire of the 13th and 14th centuries was the largest contiguous land empire in history. Originating in present-day Mongolia in East Asia, the Mongol Empire at its height stretched from the Sea of Japan to parts of Eastern Europe, extending northward into parts of the Arctic; eastward and southward into parts of the Indian subcontinent, attempted invasions of Southeast Asia, and conquered the Iranian Plateau; and westward as far as the Levant and the Carpathian Mountains.
The Mongol Empire emerged from the unification of several nomadic tribes in the Mongol homeland under the leadership of Temüjin, known by the more famous title of Genghis Khan (1162–1227), whom a council proclaimed as the ruler of all Mongols in 1206. The empire grew rapidly under his rule and that of his descendants, who sent out invading armies in every direction. The vast transcontinental empire connected the East with the West, and the Pacific to the Mediterranean, in an enforced Pax Mongolica, allowing the exchange of trade, technologies, commodities, and ideologies 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 from one of his other sons, such as Tolui, Chagatai, or Jochi. The Toluids prevailed after a bloody purge of Ögedeid and Chagatayid factions, but disputes continued among the descendants of Tolui. A key reason for the split was the dispute over whether the Mongol Empire would become a sedentary, cosmopolitan empire, or would stay true to the Mongol nomadic and steppe-based lifestyle.
After Möngke Khan died (1259), rival kurultai councils simultaneously elected different successors, the brothers Ariq Böke and Kublai Khan, who fought each other in the Toluid Civil War (1260–1264) and also dealt with challenges from the descendants of other sons of Genghis. Kublai successfully took power, but war ensued as he sought unsuccessfully to regain control of the Chagatayid and Ögedeid families.