[Sherman Logan]

It took decades, if not centuries for anyone to defeat them

Quite right. The Japanese repelled them, but largely because of storms, the famous Divine Wind (Kamikaze).

The Mamluks eventually defeated them in Palestine, but many decades after they started their rampages.

In their several invasions of Europe, they were never defeated by a European army. Each time they turned back for internal reasons.

They also failed when invading what are now Indonesia, Vietnam and Thailand, but that is fairly obviously more of a climate issue.

[Cronos]

I think they would have been stuck further into Europe -- they were good on the steppes like the Avars, Magyars, huns before them, but get past the Carpathian basin and they'd be hit by mountains etc.

btw, do you know why the Mongols so badly wanted to attack the Magyars?

I was reading about their attack on Poland and that was just a diversion -- their real target were the Magyar and I dont know why