The Eurasian steppe does not go on forever. Travel far enough to the north and you reach taiga and temperate forest. And there are mountains bordering it from the Carpathians in the west to the Greater Khingan in the east.

Also, the steppe nomads conducted extensive trade with settled peoples.

hi! this won't answer all your questions, but you may be interested in this post

Mongol Military under Genghis khan mainly consisted of Archers.But since they were living in Steppe how did they get the materials for their Arrows? And how did they replenish the arrows during a war in a distant country?