In the Mongol siege of Kaifeng from 1232 to 1233, the Mongol Empire captured Kaifeng, the capital of the Jurchen Jin Dynasty. The Mongols and Jurchens had been at war for nearly two decades, beginning in 1211 after the Jurchens refused the Mongol offer to submit as a vassal. Ögedei Khan sent two armies to besiege Kaifeng, one led by himself, and the other by his brother Tolui. Command of the forces, once they converged into a single army, was given to Subutai who led the siege. The Mongols arrived at the walls of Kaifeng on April 8, 1232.