The Empire of Genghis Khan
The Empire of Genghis Khan, the greatest in extent the world has ever seen (it was six thousand miles from east to west and about two thousand at its widest). Before Genghis the Mongols had been obscure horse nomads on the high prairies of Mongolia, southeast of Lake Baikal. Accustomed to endure every privation, to live in the saddle, to strike their enemies without mercy, they needed only to be disciplined as a military force and aroused by the taste of conquest to become invincible. A certain chieftain named Temuchin gave them that discipline and that taste. By the 
time he was forty-four, in 1206, he had become Genghis Khan, ” The Universal Lord.” His formula was simple: his force was horseman- truly half man half horse- who combined maximum mobility with iron stamina and discipline; his practice was to annihilate the enemy down to the very cats and dogs and to obliterate communities to a point where in a few instances, horses could be grazed on the site; and his one aim in life was conquest. At his death in 1227 he was master of most of Asia from Peiping in the east to Georgia in the West and Afghanistan to the south.
The Son who succeeded him
Ogodai, the son who succeeded him, extended the empire southward into China. At the same time , Batu, the son of Ogodai’s half-brother, Juchi, together with one of Genghis’ old Generals, Subotai, swept savagely westward, sacked 
Kiev and other Russian cities, burst into Poland and leveled Kracow. In the spring of 1241, in Hungary, they routed an army of 100,000 barons knights and infantry, the best that eastern Europe could muster, and proceeded to devastate Pest on the Danube.By the following winter one column, swinging south, reached Dalmatia, so that by December they stood on the shores of both the Danube and the Adriatic.
European reaction to the Mongols
The typical general reaction to the Mongols could be described through writing of monk Matthew Paris:
In this year (1240), a detestable nation of Satan…. the Tartars, broke loose from the mountain-environed home, and piercing the solid rocks, poured forth like devils…. They are thirsting for and drinking blood, tearing and devouring the flesh of dogs and men, dressed in oxhides, armed with plates of iron, thickest, strong, invincible.
After the death of Ogodai
At a critical moment Ogodai died, and the heads of the clan were summoned to a meeting in Mongolia. While Europe hung in the balance, Batu and Subotai debated and then withdrew, Subotai going back to Mongolia, Batu retiring to his court on the Volga and the arms of his 26 wives. Had Ogodai not died, it is possible that the Mongols would have overrun Europe. By this time the Mongol empire had become so vast that although the eastern part remained the homeland, great segments came under the rule, more or less independent- and not without quarrels and clashes of various members of the family.
The fractured Empire
Ogodai’s son Kuyuk was Great khan only briefly, dying in 1248, and another grandson of Genghis, Mangu, ruled from 1252 to 1259. Meanwhile Batu, Khan of the Golden Horde, remained lord of the west and Hulaku, another grandson of Genghis, became lord from Eastern Persia to the Mediterranean. It was Hulaku who in 1268 captured the last Caliph of Baghdad and did such destruction in that magnificent city that it never recovered. He conquered Damascus and Jerusalem and was threatening Egypt when once again the death of a Great Khan, this time Mangu stopped what might have been a decisive blow. This time the fate of the Levant, of Moslem power, and the Crusaders themselves hung in the balance. Like Batu before him, however Hulaku turned back.
The Rise of a Great figure in the East
A Great figure emerges in the east, Kublai, a younger brother of Mangu. Brought up partly under the influence of a few Chinese advisers he had been later send to extend Mongol dominion farther into China. And he had done so. But the more he saw of the Chinese way of life, the more he appears to have been influenced by it. The sung emperors
had ruled for over 300 years and had turned increasingly to the contemplation of spiritual values and an appreciation of the arts. Under their reign the great walled cities south of the Yangtze had grown even greater. When Mangu died Kublai taking advantage of the decision among the khans, caused himself to be elected as Great Khan. Before long he had Completed the conquest of China all the way to Canton and the southern seas, accomplishing much of this by cunning rather then by force. His inclination was not to destroy but assimilate what he found. Where Genghis had been the warrior, the ruthless conqueror, the military genius, Kublai was the statesman , the administrator, cultivator of values, lover of refinement. By the time of his death in 1294, after 34 years on the throne, he had been transformed from a heroic to a divine figure, from a khan of the Mongols to a son of Heaven, inheritor of the Dragon throne before whom multitudes of courtiers fell prostrate when cry arose ”Bow and Adore!”