From the 1220s into the 1240s, the Mongols conquered the Turkic states of Volga Bulgaria, Cumania, Alania, and the Kievan Rus' federation. Following this, they began their invasion into heartland Europe by launching a two-pronged invasion of then-fragmented Poland, culminating in the Battle of Legnica (9 April 1241), and the Kingdom of Hungary, culminating in the Battle of Mohi (11 April 1241). Invasions also were launched into the Caucasus against the Kingdom of Georgia and the Chechens and Ingush, as well as into the Southeast Europe against Bulgaria, Croatia, and the Latin Empire. The operations were planned by General Subutai (1175–1248) and commanded by Batu Khan ( 1207–1255) and Kadan (d. 1261). Both of the latter were grandsons of Genghis Khan. Their conquests integrated much of Eastern European territory into the empire of the Golden Horde. Warring European princes realized they had to cooperate in the face of a Mongol invasion, so local wars and conflicts were suspended in parts of central Europe, only to be resumed after the Mongols had withdrawn. After the initial invasions, subsequent raids and punitive expeditions continued into the late 13th century. General overview Invasions and conquest of Kievan Rus' In 1223, Mongols routed a near 50,000 Rus'/Cuman army at the Battle of the Kalka River near modern-day Mariupol before turning back for nearly a decade. Ögedei Khan ordered Batu Khan to conquer Rus' in 1235. The main force, headed by Jochi's sons, and their cousins, Möngke Khan and Güyük Khan, arrived at Ryazan in December 1237. Ryazan refused to surrender, and the Mongols sacked it and then stormed Suzdalia. Many Rus' armies were defeated; Grand Prince Yuri was killed on the Sit River (March 4, 1238). Major cities such as Vladimir, Torzhok, and Kozelsk were captured. Afterward, the Mongols turned their attention to the steppe, crushing the Kypchaks and the Alans and sacking Crimea. Batu appeared in Kievan Rus' in 1239, sacking Pereiaslav and Chernihiv. The Mongols sacked Kiev on December 6, 1240, destroyed Sutiejsk and conquered Halych along with Volodymyr-Volynskyi. Batu sent a small detachment to probe the Poles before passing on to Central Europe. One column was routed by the Poles while the other defeated the Polish army and returned. Invasion of Central Europe The attack on Europe was planned and executed by Subutai, who achieved perhaps his most lasting fame with his victories there. Having devastated the various Rus' principalities, he