Historians estimate Statement that up to half of Hungary 's then population of 2,000,000 were victims Death of the Mongol invasion Ottokar 's troops consisted of Bohemian-Moravian , German , Polish , Carinthian , Carniolan and Styrian forces , while Bela 's huge army gathered Come_together Hungarian , Slovak , Cuman , Russian , Polish , Bulgarian , Wallachian , Ukrainian ( Galician ) , Slavonian , Croatian , Bosnian , Serbian , Pecheneg and Szekler contingents .