AOA
Genghis Khan or Temüjin (1162–1227) united many tribes of Mongols and made a decisive battle force. When Genghis Khan died, a major potential weakness of the system he had set up manifested itself. It took many months to summon the kurultai (council), as many of its most important members were leading military campaigns thousands of miles from the Mongol heartland. And then it took months more for the kurultai to come to the decision that had been almost inevitable from the start — that Genghis's choice as successor, his third son Ögedei, should become Great Khan. Ögedei was a rather passive ruler and personally self-indulgent, but he was intelligent, charming and a good decision-maker whose authority was respected throughout his reign by apparently stronger-willed relatives and generals whom he had inherited from Genghis.
On Ögedei's death in 1241, however, the system started falling apart. Pending a kurultai to elect Ögedei's successor, his widow Toregene Khatun assumed power and proceeded to ensure the election of her son Guyuk by the kurultai. Batu was unwilling to accept Guyuk as Great Khan, but lacked the influence in the kurultai to procure his own election. Therefore, while moving no further west, he simultaneously insisted that the situation in Europe was too precarious for him to come east and that he could not accept the result of any kurultai held in his absence. The resulting stalemate lasted four years. In 1246 Batu eventually agreed to send a representative to the kurultai but never acknowledged the resulting election of Guyuk as Great Khan.
Guyuk died in 1248, only two years after his election, on his way west, apparently to force Batu to acknowledge his authority, and his widow Oghul Ghaymish assumed the regency pending the meeting of the kurultai; unfortunately for her, she could not keep the power. Batu remained in the west but this time gave his support to his and Guyuk's cousin, Möngke, who was duly elected Great Khan in 1251.
Möngke Khan unwittingly provided his brother Kublai, or Qubilai, with a chance to become Khan in 1260, assigning Kublai to a province in North China. Kublai expanded the Mongol empire and became a favorite of Möngke. Kublai's conquest of China is estimated by Holworth, based on census figures, to have killed over 18 million people.
Later, though, when Kublai began to adopt many Chinese laws and customs, his brother was persuaded by his advisors that Kublai was becoming too Chinese and would become treasonous. Möngke kept a closer watch on Kublai from then on but died campaigning in the west. After his older brother's death, Kublai placed himself in the running for a new khan against his younger brother, and, although his younger brother won the election, Kublai defeated him in battle, and Kublai became the last true Great Khan.
He proved to be a strong warrior, but his critics still accused him of being too closely tied to Chinese culture. When he moved his headquarters to Beijing, there was an uprising in the old capital that he barely staunched. He focused mostly on foreign alliances, and opened trade routes. He dined with a large court every day, and met with many ambassadors, foreign merchants, and even offered to convert to Christianity if this religion was proved to be correct by 100 priests.
By the reign of Kublai Khan, the empire was already in the process of splitting into a number of smaller khanates. After Kublai died in 1294, his heirs failed to maintain the Pax Mongolica and the Silk Road closed. Inter-family rivalry compounded by the complicated politics of succession, which twice paralyzed military operations as far off as Hungary and the borders of Egypt (crippling their chances of success), and the tendencies of some of the khans to drink themselves to death fairly young (causing the aforementioned succession crises), hastened the disintegration of the empire.
Another factor which contributed to the disintegration was the decline of morale when the capital was moved from Karakorum to modern day Beijing by Kublai Khan, because Kublai Khan associated more with Chinese culture. Kublai concentrated on the war with the Song Dynasty, assuming the mantle of ruler of China, while the more Western khanates gradually drifted away.
The four descendant empires were the Mongol-founded Yuan Dynasty in China, the Chagatai Khanate, the Golden Horde that controlled Central Asia and Russia, and the Ilkhans who ruled Persia from 1256 to 1353. Of the latter, their ruler Ilkhan Ghazan was converted to Islam in 1295 and actively supported the expansion of this religion in his empire.
plz follow the following link for complete information:
http://en.wikipedia.org/wiki/Mongol_Empire