The Mongols lead by Guyuk Khan invaded the Byzantine province of Crimea in 1241, as part of their plan to invade Europe and expand the Mongol Empire across the world. But the Byzantines in the Crimea proved a challenge as the Mongols were originally defeated in their attempt to capture Kerch, and were then forced on to the Crimean by land up north. The city of Simferopol fell in May 1241, and eventually Yalta, the Byzantines retreated from the peninsula finally in June, but destroyed all the ports, leaving the Mongols stranded on the Crimea.