In 1255 a new wave of conquest rolled westward from Mongolia, this time directed against the Ismaelians or "Assassins" on the south of the Caspian, and then successively against the Khalif of Baghdad and Syria. The conclusion of this expedition under Hulagu may be considered to mark the climax of the Mongol power. Mangu Khan, the emperor then reigning, and who died on a campaign in China in 1259, was the last who exercised a sovereignty so nearly universal. His successor Kublai extended indeed largely the frontiers of the Mongol power in China, which he brought entirely under the yoke, besides gaining conquests rather nominal than real on its southern and south eastern borders, but he ruled effectively only in the eastern regions of the great empire, which had now broken up into four. (1) The immediate Empire of the Great Khan, seated eventually at Khanbalik or Peking, embraced China, Corea, Mongolia, and Manchuria, Tibet, and claims at least over Tunking and countries on the Ava frontier ; (2), the Chagatai Khanate, or Middle Empire of the Tartars, with its capital at Almalik, included the modern Dsungaria, part of Chinese Turkestan, Transoxiana, and Afghanistan ; (3), the Empire of Kipchak, or the Northern Tartars, founded on the conquests of Batu, and with its chief seat at Sarai on the Wolga, covered a large part of Russia, the country north of Caucasus, Khwarizm, and a part of the modern.Siberia; (4), Persia, with its capital eventually at Tabriz, embraced Georgia, Armenia, Azerbaijan and part of Asia Minor, all Persia, Arabian Irak, and Khorasan.