Originally Posted by blackhole

Mongols invaded in about 1250 Russia , E.Europe but then Khan died and retreated back to the far east.
I agree Mongols defeated Polish, Silesian,Moravian armees but mainly in my view by the sheer numbers of their soldiers and in fact they had good tactic "Mongol Blitz" I would call.
But that happened in early 12-century,later on European metallurgy surpassed and weaponry was simply the best in the world.Knights were just unbeaten in the field,they conquered whole of Iberian peninsula from lightly armoured and fast Arabs.
Look at the Teutonic order in early 15-century with their couple of thousand heavy cavalry.They blackmailed and defeated many times powerfull Kings of Poland and Lithauenia.
Teutonic order was mainly German and as I mentioned before German armour was the best and also discipline and tactics.Knights rule!