Here more... Reason why Mongols gave up on Hungary... Remember everyone says mongols stop one invasion because the Mongols had to elect a new leader but Bstu never went back to the Mongol capital...
The Mongol invasion of Eastern Europe and especially its sudden withdrawal from Hungary in 1242 CE, has generated much speculation and an array of controversial theories. None of them, however, considered multifaceted environmental drivers and the coupled analysis of historical reports and...
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No reason is given in the Mongol sources to explain their abrupt departure from Hungary. Following a note in the report made by a papal legate, Friar Giovanni da Pian del Carpine, who visited the court of Güyük Khan in 1246 (successor of Ögödei, r. 1246–1248), many historians for a long time believed, that the Mongol withdrawal (MW) was due to the death of Great Khan Ögödei in December 1241 CE8. The ensuing political upheaval would have forced Batu to halt operations and return to Karakorum, the capital of the empire in Mongolia, to participate in political meetings to elect the new khan. This hypothesis, however, has been challenged on grounds that Batu never went back to Mongolia and instead remained in the southern Russian steppes where he consolidated his power as ruler of the Golden Horde9.