- Ogedai Khagan died in 1241, right after the Battle of Tisza River. All the Khans under Mongol Khagan‘s rule and clan leaders had to ride back to Karakorum to chose a new Khagan. After he returned, Batu decided no to push west, instead he kept ruling Golden Horde and invaded northwest, the Rus’ states. Batu Khan of Golden Horde thought he should have been chosen as Khagan but instead, Guyuk son of Ogedei was chosen. Golden Horde was about to rebel against the Mongol Empire, the tension was rising. Guyuk died several years later. After Guyuk, again, Mongke was chosen instead of Batu but Batu died four years later so the dusts was settled.
- Mongke wanted to take whole China instead since the Europe was seen as a poor and unnecessary region. I can’t say they were wrong for Middle-Ages. Mongke’s successor Kublai was sharing the same ideology, he used his full power over the east and conquered all of China.
- Kaidu, de facto khan of Ogedeids and a grandson of Genghis who was not okay with Mongol Empire becoming more “Chinese” since Kublai carried the capital from their homelands, from the steppes, from Karakorum to Khanbaliq(Beijing) wanted Mongol Khagan to be judged in a trial kurultai, accusing him with treachery against Mongols but Kublai was chosen again by the kurultai so they rebeled against the Empire, allying with Chagataids. The connection between Western Khanates and Eastern Khanates were ripped of. Mongol Empire were divided. Western Khanates became independent right after. Areas controlled by Great Khan and his successors like China got the name “Yuan Dynasty”, Ilkhanates, Ogedeids, Chagataids and Golden Horde became independent too so Mongol Empire divided. Mongols were strong together and armies was splitted after the division too so they never became that strong ever again. The westernmost khanate, Golden Horde Turkified under the enormous Kipchak population. Lately, it splitted after never ending civil wars to Khanates like Crimean Khanate which became a vassal of the Ottoman Empire.
There were several more reasons, of course:
- Mongols didn’t have the proper siege technology, they weren’t controlling a single castle in Europe because they didn’t know how to do a siege, they just won in field wars.
- Logistics wasn’t enought to gather all the manpower in the west, we are talking about armies almost 6000 kilometers far from the capital. How far they were from home, that much weak the armies were.
I saw some statements like “because Europeans stood still and they were strong” all across the internet but no. If the same exhausted army could have won against Hungarians, Polish, Moravians and Teutonic Order in 2 great battles like Legnica and Tisza River easily just in 2 days intervals 6000 kilometers far from their home, you’re weak.