In 1220 Genghis Khan seized Persia; in 1234 his successors routed the entire Seljuk army and went on to occupy the sultanate of Rum. In 1258 Gengis Khan’s grandson Hulagu captured Baghdad and eliminated the last ghostly relic of the Abbasid caliphate, as his armies complete the destruction of the great irrigation works of Mesopotamia. Mansfield, Peter, A History of the Middle East, New York- Penguin Books, 1991. See also- Hulegu Enters Jerusalem, 1260