The northern slopes of Gyala Peri and the peaks beyond the Tsangpo, sometimes included in the Himalayas, drain into the Irrawaddy River, which originates in eastern Tibet and flows south through Myanmar to drain into the Andaman Sea. The Salween, Mekong, Yangtze and Yellow River all originate from parts of the Tibetan Plateau that are geologically distinct from the Himalaya mountains and are therefore not considered true Himalayan rivers. Some geologists refer to all the rivers collectively as the circum-Himalayan rivers.