For every great conqueror who emerged from the steppes of central Asia, the prerequisite was consolidation of the unruly and warlike tribes of their homelands. The founder of the Seljuk Empire, Tughrul, would perform this feat with the Turkic tribes north of Transoxiana in the 1020s; he then turned on the foremost regional power, the Ghaznavids, who controlled Persia, achieving a decisive victory at the Battle of Dandangan (1040). He then surged west through Nishapur and Kermanshah to seize Baghdad (when his brother led a rebellion there, Tughrul personally strangled him with a bowstring), finally attacking the Byzantines. Tughrul’s son Alp Arslan won a decisive victory over the Byzantines at Manzikert (1071), but within three decades, the empire was divided by dynastic strife, enabling the crusaders to establish the kingdom of Jerusalem. The eastern empire was briefly reunited under the Shah of Khwarizm – until he made the mistake of insulting Genghis Khan (1220).
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