Northern column of the Mongol forces was supported by a large contingent of the Mongol vassals, Ruthenians, under Duke Mstislav of Lutsk, Duke Volodymir of Volhynia, and Duke Lev of Halicz. Altogether, the invading forces numbered some 30,000 warriors, with 20,000 attacking the north and 10,000 targeting the south. Leszek II the Black stood opposed to the Mongols with probably 15,000 strong. Furthermore, in comparison to the second invasion, several towns and cities had been fortified.