As you guys said, the Mongols were interested in money. And the Mongols, in the 13-14th century did interfere quite a bit in Russian politics at the time. Hell, one Golden Horde Khan even interfered with Hungarian politics even after the invasion!
But fortifications would not have held long anyway. Chinese amd Muslim siege experts would take care of anything in no time. And W. Europe have no armies left to kill Mongols. The battle of Liegnitz finished off a big German-Franco-Polish force, another battle within two days finished off a big Hungarian-Teutonic force. And if terrain did not suit them, the Mongols were very willing to accept any troops who did not feel like dying for their country (as was the case in China - the Southern Sung would not have fallen if the navy had not defected).
There's this book, "THe Mongols" by David Morgan. IT's bloody good. He discusses everything from Genghis' unification to military structure to communications to the effects of the Mongols on history.
But fortifications would not have held long anyway. Chinese amd Muslim siege experts would take care of anything in no time. And W. Europe have no armies left to kill Mongols. The battle of Liegnitz finished off a big German-Franco-Polish force, another battle within two days finished off a big Hungarian-Teutonic force. And if terrain did not suit them, the Mongols were very willing to accept any troops who did not feel like dying for their country (as was the case in China - the Southern Sung would not have fallen if the navy had not defected).
There's this book, "THe Mongols" by David Morgan. IT's bloody good. He discusses everything from Genghis' unification to military structure to communications to the effects of the Mongols on history.