Berke was a grandson of Genghis Khan and a brother of Batu, and he took over the Golden Horde after Batu's death. Travelling among the cities of Central Asia he accepted Islam, the first Mongol ruler to do so. The choice was more than personal: Muslim merchants and scholars gathered at Sarai, and the khanate drew closer to the Islamic world.
When his cousin Hülegü sacked Baghdad in 1258 and executed the caliph, the leader of the Islamic world, Berke was enraged. Against a fellow Mongol he allied with the Mamluk sultanate of Egypt — the first time a Mongol prince made common cause with an outside power to fight his own family.
The khanate he ruled held both the river traffic of the Volga and the caravan roads of the steppe. Furs, salt and grain gathered at his capital, Sarai, and the alliance with the Mamluks of Egypt rested on trade as much as on faith: the Mamluks needed young men from the steppe for their armies, and Berke controlled the road they travelled.
From 1262 the two men fought in the Caucasus. In January 1263 his army beat Hülegü badly at the Terek River, where the ice broke beneath the retreating enemy and many drowned. Berke set out against the Ilkhanate again in 1266 but fell ill and died on the road to Tiflis, and Mengu-Timur succeeded him. The line he drew between Mongol kinsmen along the border of faith outlasted him by a long way.