A pair of researchers has found a possible explanation for the sudden,mysterious reason that the Mongol army withdrew from Eastern Europe in 1242, just when it seemed poised to take Hungary. In their paper published in the journal Nature, and Ulf Büntgen with the Swiss Federal Research Institute and Nicola Di Cosmo with the Institute for Advanced Study in the U.
S. relate a study they made of tree ring data from trees in Hungary and historical records,which showed that the weather during the time of the Mongol invasion was not particularly well suited for an army traveling on horseback.
Source: phys.org