In April 1241 the Mongol army destroyed Béla IV's forces at Mohi and spent the following year systematically ravaging Hungary, crossing the frozen Danube in the winter to reach Transdanubia before withdrawing in spring 1242 after Ögedei's death. Master Roger's Carmen miserabile, written by a survivor, describes massacre, the burning of settlements and a famine in which the surviving population starved. The scale of loss is disputed. Britannica's summary reports that Hungary lost about half its population, with roughly sixty per cent losses on the Great Plain — locally total — and about twenty per cent in Transdanubia, figures derived from settlement archaeology and the disappearance of villages from later charters. Other Hungarian historians argue for a considerably lower overall loss, in the range of fifteen to twenty per cent, holding that many settlements recorded as abandoned were re-established and that the charter evidence overstates permanent depopulation. Hungary's population before the invasion is usually put at around two million.
Batu's and Subutai's Mongol armies destroyed the Hungarian royal army at Mohi and devastated the kingdom for a year before withdrawing on the death of the Great Khan Ögedei
Hungarian historical demography reconstructs the kingdom's mid-thirteenth-century population from later charters, settlement archaeology and the tax registers of the following century. György Györffy and others put it at roughly 2 million, with published estimates ranging from about 1.5 to 2.5 million. Estimates of the invasion's mortality — from 15 to 50 per cent, varying sharply between the Great Plain and the forested and mountainous regions — are correspondingly uncertain.
The range applies the competing loss estimates to a pre-invasion population usually put at about two million: the lower end reflects historians who argue for fifteen to twenty per cent loss, the upper the reading reported by Britannica that Hungary lost about half its people. Deaths from the ensuing famine of 1242, described by Master Roger, are included and cannot be separated from those killed outright.
Massacre, the burning of settlements and the famine of 1242 are documented by Master Roger of Torre Maggiore's Carmen miserabile, written by an eyewitness who was himself captured.
Hungary, Bosnia and Herz.