During the invasion of the Khwarezm Empire in 1219, Jebe was sent with a diversionary force over the Tian Shan mountains during the winter to threaten the fertile Ferghana Valley. Jebe was able to navigate the tall mountain passes that had over five feet of snow, and he drew out Shah Mohammed II's elite 50,000 man cavalry reserve force. Jebe either won a victory or at least avoided defeat against this elite force and maneuvered further south to threaten Khorasan in order to cut off the far-away provinces. He then looped back to join Genghis's main army at the capital Samarkand, effectively dividing Khwarezm into two. In order to prevent the Shah from rallying his forces in Khorasan and western Iran, Genghis Khan dispatched Jebe and Subutai to hunt the Shah throughout his own empire. Though they ultimately failed to catch him, their close pursuit prevented the Shah from rallying any new armies and the Shah was forced to flee toward Iran with Jebe and Subutai in close behind. As a result, the Khwarezmian forces were spread out and destroyed gradually.