A map. A key shows Empire of the Great Khan in orange, Il-Khanate in green, Khanate of the Golden Horde in yellow, and Chagatai Khanate in purple. Mongolia, most of China, Tibet, and the Korean peninsula are orange. Parts of South and Southwest Asia are green. Central Asia through much of Eastern Europe are yellow. Part of Central Asia including parts of Western China and Tibet are purple. Which event most directly led to the divisions shown on the map?

death of Ögödei Khan
spread of the bubonic plague
adoption of Islam by two khans
attacks by Russians, Turks, and Chinese