Historically, geographic isolation inhibited economic development in Rapti Zone. Trans-himalayan trade routes lay to the east along the Kaligandaki River and to the west along the Bheri and Karnali. Compared to these, a hypothetical transhimalayan trade route through Rapti would have been impeded by a wide Inner Terai malarial belt, by ridges up to 4,000 meters exiting the Rapti watershed, then by the Dhaulagiri Himalayas and the only comparatively lower Kagmara and Tibetan border ranges before reaching the Tibetan Plateau.