Climate of doubt: A re-evaluation of Büntgen and Di Cosmo’s environmental hypothesis for the Mongol withdrawal from Hungary, 1242 CE

TL;DR

This paper re-evaluates Büntgen and Di Cosmo’s environmental hypothesis that wet, marshy conditions in early 1242 forced the Mongol withdrawal from Hungary. It argues that environmental, archaeological, and historical evidence instead suggests the Mongols could sustain themselves in Hungary and that the withdrawal cannot be explained largely by climatic factors.

Key findings

• The wet spring of 1242 likely improved rather than worsened Mongol prospects: spring inundations raise grass yields in temperate grasslands, and a relatively low-precipitation period followed by a wet spring should have increased crop yields countrywide.
• The “great famine” in Hungary was man-made, caused by Mongol destruction and displacement, not climate: medieval writers said farmers could not plant or harvest for two growing seasons because of the Tatars, and the Mongols left with loaded wagons after plundering livestock and horses.
• The Hungarian Plain could sustain large herds: the 110,000 km² plain had long attracted nomadic herders; in a 200 km² pasture near Debrecen in 1770–72, 13,500 cattle, 1,100 horses, and 18,000 sheep were registered, and in 1861 six Cuman settlements (ca. 1% of the plain) had 30,593 cattle, 15,190 horses, 245,340 sheep, and 26,100 pigs.
• King Béla IV’s letter to the pope states the Mongols “can settle their families and animals – in which they abound – marvellously well here [in Hungary], better than elsewhere,” undermining claims of insufficient fodder.
• Archaeological evidence shows the most heavily affected areas were in the Great Plain and plains west of the Danube, with 1241–1242 coin hoards in the same regions, so there is no evidence Mongol forces were impeded in the wet-affected plain areas.

Methods

• Design: a critical re-evaluation and rebuttal of Büntgen and Di Cosmo’s environmental hypothesis, using environmental, archaeological, and historical evidence.
• Data/sample: historical sources including King Béla IV’s letter to the pope, Rogerius, Thomas of Split, Ibn al-Athir, and Mongol-Chinese government sources; archaeological evidence from Mongol invasion sites and 1241–1242 coin hoards; livestock censuses from 1770–72 and 1861; and 1921–2010 Hungarian crop yield and March–August precipitation data.
• Main analysis: qualitative and analogical comparison of the environmental hypothesis against documentary, archaeological, and later quantitative agricultural evidence, including a scatter plot showing a positive correlation between March–August precipitation and yields of four crops in Hungary from 1921–2010.

Limitations

• Stated: “there are no quantitative data on precipitation for 1241–1242 that allow a valid comparison of 13th and 20th century conditions.”
• Stated: sources offer little detail on why the Mongols took nine months to cross the Danube after Mohi.
• Evident: the argument relies heavily on qualitative historical sources and later-period analogies, so it cannot directly measure 1242 environmental conditions or definitively establish Mongol motivations.