The passes in these high mountains linked India with outside world When the powerful dynasties declined these passes were left unguarded and invited foreign invasions.
The Pilgrims were the English settlers who came to North America on the Mayflower and established the Plymouth Colony in what is today Plymouth, Massachusetts, named after the final departure port of Plymouth, Devon.
Theravada spread and became popular in Southeast Asian region of Sri Lanka, Myanmar, Thailand and Indonesia etc.
Buddhism spread to western and southern India were in western Ghats Buddhist hill cave were carved out by merchants and farmers or at Kings or Queens order.
Chinese Buddhist pilgrims visited India to study Buddhist text meet Buddhism scholars and then carry them back to China. They wrote accounts of their journeys to India.