Thirteenth century could be the perfect time for invading politically divided Europe. One of the main powers of the continent which were Holy Roman Empire, Papacy, Hungarian Kingdom and Poland had strong conflicts among each other. During the Mongol Invasion, there were power struggle between Holy Roman Emperor Frederick II. and the Papacy in Europe. To Central Eastern Europe, Hungarian Kingdom and Poland had internal struggles. Also, Poland divided to four principality, Hungarian Kingdom had economic problems therefore, the King did not have absolute control on his Barons at the country. This study aims to reveal the effects of Mongol Invasion on the Hungarian Kingdom in the following sections: Mongol history, military structure and their expeditions to Europe. Hungarian history, the conquest of Carpathian Basin, the Christianization of the Hungarians and the Golden Bull which was important for Hungarian internal affairs. Also, The Medieval European military structure during the Mongol Invasion period. Battle of Móhi. Also, situation of the Hungarian Kingdom after the Mongol Invasion and the effects of the Battle of Móhi.