Geography doesn't just determine whether humans can live in a certain area or not, it also determines people's lifestyles, as they adapt to the available food and climate patterns. As humans have migrated across the planet, they have had to adapt to all the changing conditions they were exposed to.
The Himalayas separate India from the rest of Asia to the east and west. But, you can still go through by foot because of the passes which is good to visitors, but bad for invasions. It is also heavily influenced by the Indus and Ganges rivers. If the monsoons bring too little water for the crops, the crops suffer; too much rain and deadly floods occur.
