The Russians were a) standing next to the mongols, b) were closer and more accessible than Hungry.
As for low grasslands... Europe was covered in Forrest. It's why a whole swath of the central Europe used to be called : The Black Forest. It was a big, dark, thick forest. Paris and Madrid simply aren't worth the effort compared to Constantinople.
Considering the Muslim's fight with the Mongols, the Christians probably would have lost, as the Muslims barely survived on their own territory, with highly unified and competent commanders, and benefited from Mongol infighting after the death of the Khan.
Also, the Hungarians were one of the better forces in Europe.
Most of the time, the Christians spent consolidating their forces and letting (or bribing) the Mongols to aim at the Muslims.
The Russians were a) standing next to the mongols, b) were closer and more accessible than Hungry.
As for low grasslands... Europe was covered in Forrest. It's why a whole swath of the central Europe used to be called : The Black Forest. It was a big, dark, thick forest. Paris and Madrid simply aren't worth the effort compared to Constantinople.
Considering the Muslim's fight with the Mongols, the Christians probably would have lost, as the Muslims barely survived on their own territory, with highly unified and competent commanders, and benefited from Mongol infighting after the death of the Khan.
Also, the Hungarians were one of the better forces in Europe.
Most of the time, the Christians spent consolidating their forces and letting (or bribing) the Mongols to aim at the Muslims.