From memory, wasnt it the Hungarian king who after they got massively destroyed by the Mongols, dedicated his life to preparing defences and then years after his death they came back and were sucessfully pushed back?

I’m actually not super up on Hungarian history, but I do know that the Hungarian monarch at the time, after returning from self-imposed exile, invested massively in fortifications, since fortifications were one of the few things that did slow the first invasion.

Also funny to think Western Europe viewed the Mongols as potential Christian allies at the start lol. Their face once Mongels got to Eastern Europe:

Depending on your point of view, it might get funnier - a few decades after this, there were serious discussions of making an alliance with one of the Mongol successor states. If memory serves, sectarian divisions (Christian Mongols tended to be Nestorian, rather than Catholic or Orthodox) and clashing egos eventually sunk the plan, despite their common foe of the Muslim Caliphates.