While the invasion of the Khwarezmian Empire was going on, Genghis Khan sent his best generals Subutai and Jebe to chase down the Shah of Khwarezm Muhammad II. Their raid into modern-day Iran, Azerbaijan, Georgia, and Armenia was lucrative, as they razed and plundered many cities, but they didn't stop there and moved into the modern Russia and Ukraine, where they fought a loose alliance of the Rus princedoms and the Kipchaks (Cuman/Pecheneg/Polovtsi) in the famous battle of Kalka in 1233. This episode also describes the dynastic situation in the Mongol empire after the death of Genghis Khan.