Hey its very simple
there is more impact of himalayaes on the environment of south asia why because himalayas are the major resource because of himalayan glaciers there are perrenial rivers for south asian countries himalayas grap the moist in the wind and allows water to rivers because of rivers there is more water for floura and fauna in this way because of himalayas there is more impact of himalayas on the go environment of the countries of south asia