Examples of impacts chain migration has on rural areas

 The himilayas are an example of an intervening obstacle, but that is an enviromental obstacle. You could have an economic obstacle such as a town along the way that may be in harsh poverty and you may not be able to continue migrating. Or a political obstacle: Migrating through a country that is ruled under a law that despises something about you like race, gender, culture, or personal status.

Answer primary waves;

No map. ie where is the map as this question cannot he answered without a map so the question as is is irrelevant and i am disappointed as i am a geologist.