Salween

Geography and naming

The Salween basin includes about 283,500 km2 (109,500 mi2), of which 48 percent is in China, 44 percent in Myanmar, and 8 percent in Thailand. The basin is extremely long and narrow, situated between the Irrawaddy and Brahmaputra river systems on the west and the Mekong system on the east, and sharing a shorter boundary with the Yangtze system to the north. With a mean elevation of 3,515 m (11,532 ft), the Salween basin includes numerous glaciated mountain ranges, and the river flows for much of its length at high elevation. In China, the Salween basin is situated in Tibet Autonomous Region and Yunnan. In Myanmar the Salween flows through Shan State, Karenni State, Karen State and Mon State.

History

Human presence along the upper Salween River dates to at least 31,000–39,000 years ago. Archeological evidence includes stone tools and animal remains discovered along the river bank in the southeastern Tibetan Plateau.

The Mon are some of the earliest inhabitants of the Salween basin within Myanmar, migrating south from China around 3000 BCE, and settling in the Salween delta and adjacent coastal areas. Agriculture was first practiced in the Salween and Irrawaddy basins around the first century BCE. Ancestors of the Karen migrated down the Salween River area from the Tibetan Plateau and northwest China starting around 1000 BCE.

Ecology

The Salween basin is home to thousands of species of plants, with the highest plant diversity found in Yunnan's Three Parallel Rivers region. The Three Parallel Rivers protected areas include the Gaoligongshan National Nature Reserve and the Nu Jiang Reserve within the Salween basin; the Gaoligongshan reserve has more than 4,300 plant species. The Nujiang Lancang Gorge alpine conifer and mixed forests, situated along the Nu River in western Yunnan, span elevations of 1,000 to 6,000 m (3,300 to 19,700 ft) and range from subtropical broadleaf evergreen to subalpine conifer forests. The rare Taiwania, one of the largest conifers in Asia, is found here along with more than twenty other conifer species.

Geology

The present course of the Salween began to form about 5 million years ago as the Indian subcontinent collided with Asia, resulting in the uplift of the Himalaya mountains and the Tibetan Plateau. Prior to the Himalaya orogeny, what are now the upper Irrawaddy, Salween, Mekong and Yangtze rivers may have all flowed into the Red River, emptying into the South China Sea. The landscape was hilly but not particularly rugged, with average elevations of 1,000 m (3,300 ft) or less. As the continents converged, a complex jumble of mountains arose, breaking the ancestral Red into different drainage systems, with the Yangtze heading east towards the Pacific, and the Mekong and Salween flowing south into what is now Thailand's Chao Phraya River.