Volga River
9. What physical feature might make an army invasion from Mongolia difficult?

Rivers and mountains.

Explanation:

Rivers and mountains are the physical features that make army invasion difficult for Mongolia because going through the rivers needs ships that can accommodate limited number of people and mountains have irregular path that make movement of army makes difficult so army invasion is difficult in these two geographical features i.e. river and mountains.

no it is not. kenya allows smoking weed.