scientists-finally-know-what-stopped-mongol-hordes-from-conquering-europe By 1240, Kiev had been sacked and the horde was rapidly advancing west. Their cavalry and siege tactics were laying waste to the cities of Europe, and, perhaps more importantly, they brought along Chinese gunpowder. This series of unqualified successes brought the vast Mongol army to Hungary in March 1241. King Bela IV fled his palace in Pest (now Budapest), and Ogodei’s armies slaughtered an estimated 1 million Hungarians: Troops, clerics, nobles, knights, and peasants. It was one of the bloodiest defeats of the medieval period. The following year, everything changed. The horde suddenly turned south, moving through modern-day Serbia, and then headed back through Russia. Though subsequent khans staged occasional raids on European cities, the major war campaign was over.
The authors sampled wood from five regions of Eurasia to track what the weather was like during the period of the Mongols’ most extensive reach. Trees are especially sensitive to small changes in climactic conditions: In wet years, they add thick layers of bark to their trunks. In dry years, the rings are thinner, reflecting the lack of water to a tree. They found the climate in Hungary and its surroundings were unusually cold and wet for about three years, from 1238 to 1241. The extra moisture and early spring thaw turned the Hungarian plains into marshes and swampland — unsuitable terrain for moving the thousands of horses the Mongol armies relied on for transportation and warfare.
As scientists gain the ability to examine the climate record in greater detail, we’re discovering more about how climate shaped history. Unusual climates probably allowed Polynesians to spread out across the South Pacific, led to the fall of an ancient metropolis in pre-colonial Mexico, and encouraged Attila the Hun’s campaign of terror against the Roman Empire 800 years before Genghis Khan. The authors conclude that their study of the Mongolian withdrawal from Hungary “illustrates the incidence of even small climate fluctuations upon a historical event.”
According to (7) “when they reached the city of Székesfevehérvár that is surrounded by marshes they could not take it because the snow and ice was about to melt”. In Croatia, Qadan could not attack the city of Trogir because the flooded area separating its walls from the land was impassable on account of the depth of the mud. The army was therefore forced to withdraw. The former shows that the thaw of the snow and ice may have caused large areas to become flooded and marshy, thus impeding or restricting the movement of the Mongols. The latter example suggests that the Mongols could not easily cope with flooded and muddy terrain. The captives of the Mongols were no longer given food, and failed harvest caused general starvation. Both the decimation and dispersal of the population caused by the Mongols20 and adverse climate conditions (cold and wet) may have been concurrent triggers for harvest failure, which reduced not only the survival rate of the local population, but also the sources of provisions for the Mongol army.
The combined effects of the war and a less favorable climate may have also caused the failure of the harvest of 1242 and the ensuing ‘great famine’ in Hungary. It should be further noted that military operations of inner Asian nomads, to which the Mongols were no exception, were normally executed in autumn and continued through the winter, while the spring and summer were seasons in which they were at their weakest and most vulnerable. Military seasonality is part and parcel with the pastoral economy upon which the Mongols depended, and with the management of its resources, primarily horses. According to contemporary sources, the Mongols did not provide forage for the horses but allowed them to graze freely in the grassland. This indicates an obvious vulnerability in case no sufficient grass was available or in easy reach.
It is therefore under conditions of (i) reduced mobility and military effectiveness; (ii) reduced fodder for the horses; and (iii) reduced victuals for the army, which in the late spring of 1242 the Mongols left Hungary. The main Mongol army withdrew towards east following the southern course of the Danube (Fig. 1), thus crossing Serbia into Bulgaria, where they obtained the submission of the king Kaliman I at Tarnovo, before crossing Wallachia and Moldavia and returning to the steppes in the lower Volga region. A secondary army under Qadan that had travelled to Dalmatia in pursuit of King Béla followed the same route, joining the main army. Some minor contingent, such as the troops that had captured Roger may have proceeded to return through Transylvania. It is difficult to say why Batu chose to return by a southern route, but it is possible that the army moved to overall dryer and higher ground along the Carpathian foothills to avoid marshy conditions. – www.nature.com
Mongols settled in areas that were ecologically suitable to their economy, lifestyle, and military needs (the Volga basin). The Hungarian branch of the campaign was one of the western campaigns under Batu. That the Mongols stayed in southern Russia and did not seriously attempt to invade eastern Europe again (with the exception of a short-lived invasion of Poland in 1259) has not been so far an object of historical inquiry. However, this paper raises the possibility that the vulnerability of the Hungarian plains to even relatively short-term climate events made it obvious that the region was unsuitable for military occupation by a large army relaying mostly on horses. It is worth noting that the Hungarian river system was prone to flooding and to creating marshlands, and only much later it became drier, thanks to drainage work undertaken by the Hapsburgs in the 19th century27,28.
Our paper shows that a possible reason why the Mongols who occupied Russia under Batu and his successors did not make further attempts to expand westward may have depended on the realization that local conditions would not have supported a prolonged occupation. While the reasons why the conquest of the West halted in southern Russia have to remain speculative in the absence of proper documentation, we should consider environmental conditions on a par with political ones, such as the civil war that engulfed the Golden Horde and the Il-Khanate in following decades.. – www.nature.com