The Mongol Horde was a rare example of excellent intelligence gathering: they would send spies posing as traders in far of countries, sometimes for a decade. When the army reached the border it was well informed of the terrain, opposing numbers and local allegiances. Having a highly mobile army that covered distances much faster certainly helped. They are more of an exception though, and the defeat of the Hungarians was owned to a few more factors.
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From @usmangabol