the capital and economic center of the Kingdom of Hungary, forcing the capital to be moved to Buda. During the winter, contrary to the traditional strategy of nomadic armies which started campaigns only in spring-time, they crossed the Danube and continued their systematic occupation, including Pannonia. They eventually reached the Austrian borders and the Adriatic shores in Dalmatia. The Mongols appointed a darughachi in Hungary and minted coins in the name of Khagan. According to Michael Prawdin, the country of Béla was assigned to Orda by Batu as an appanage. At least 20–40% of the population died, by slaughter or epidemic. Rogerius of Apulia, an Italian monk and chronicler who witnessed and survived the invasion, pointed out not only the genocidal element of the occupation, but also that the Mongols especially "found pleasure" in humiliating local women. But while the Mongols claimed control of Hungary, they could not occupy fortified cities such as Fehérvár, Veszprém, Tihany, Győr, Pannonhalma, Moson, Sopron, Vasvár, Újhely, Zala, Léka, Pozsony , Nyitra, Komárom, Fülek and Abaújvár. Learning from this lesson, fortresses came to play a significant role in Hungary. King Béla IV rebuilt the country and invested in fortifications. Facing a shortage of money, he welcomed the settlement of Jewish families, investors, and tradesmen, granting them citizenship rights. The King also welcomed tens of thousands of Kun (Cumans) who had fled the country before the invasion. Chinese fire arrows were deployed by Mongols against the city of Buda on December 25, 1241, which they overran. The Mongolian invasion taught the Magyars a simple lesson: although the Mongols had destroyed the countryside, the forts and fortified cities had survived. To improve their defense capabilities for the future, they had to build forts, not only on the borders but also inside the country. In the siege of Esztergom, the defenses managed to hold off the Mongolians despite the latter having overwhelming numerical superiority and 30 siege machines which they had just used to reduce the wooden towers of the city. During the remaining decades of the 13th century and throughout the 14th century, the kings donated more and more royal land to the magnates with the condition that they build forts and ensure their defenses. Invasion of Croatia During the Middle Ages, the Kingdom of Croatia was in a personal union with the Kingdom of Hungary, with Béla IV as a king. When routed on the banks