Mountain regions (e.g., Solu) have adapted to cold/altitude: traditions like yak herding, Tibetan Buddhism, and Sherpa festivals reflect trans-Himalayan trade routes. Terai plains (e.g., Janakpur) show Maithili influences: agriculture-based Chhath festival, Madhesi cuisine using rice/lentils, and warmer-climate clothing. Geographic isolation preserved distinct languages/dress, while trade routes facilitated cultural exchange.