Just a few kilometres west of Cho Oyu is Nangpa La (5,716m/18,753 ft), a glaciated pass that serves as the main trading route between the Tibetans and the Khumbu's Sherpas. This pass separates the Khumbu and Rolwaling Himalayas. Due to its proximity to this pass and the generally moderate slopes of the standard northwest ridge route, Cho Oyu is considered the easiest 8,000 metre peak to climb. It is a popular objective for professionally guided parties.