text: Mongol invasions The following year, with the advancing Mongols, Michael, the grand prince of Kiev, who was married to Daniel's sister, quickly left Kiev and petitioned Daniel for help. Daniel dispatched his voivode, Dmytro, to defend the city. However, after a long siege, its walls were breached and, despite fierce fighting within the city, Kiev fell on 6 December 1240 and was largely destroyed. A year later, the Mongols passed through Galicia and Volhynia while campaigning against the Poles and Hungarians, destroying Galicia in the process.
  On 17 August 1245, Daniel defeated a combined force of the prince of Chernigov, disaffected boyars, and Hungarian and Polish elements at Yaroslav, and finally took the remainder of Galicia, thus reconstituting his father's holdings. He made his brother Vasylko the ruler of Volhynia and retained the Galician title for himself, though he continued to exercise real power in both places.
  Daniel's domestic policies focused on stability and economic growth. During his rule, German, Polish, and Rus' merchants and artisans were invited into Galicia, and numbers of Armenians and Jews established themselves in the towns and cities. Daniel founded the towns of Lviv (1256) and Kholm, naming the former for his son, and fortified many others. He appointed officials to protect the peasantry from aristocratic exploitation and formed peasant-based heavy infantry units.