The Nu people are one of the 56 ethnic groups recognized by the People's Republic of China. Their population of 27,000 is divided into the Northern, Central and Southern groups. Their homeland is a country of high mountains and deep ravines crossed by the Dulong, Irrawaddy, and Nujiang rivers. The name "Nu" comes from the fact that they were living near the Nujiang river, and the name of their ethnic group derives from there.

The Salween is a Southeast Asian river, about 3,289 kilometres (2,044 mi) long, flowing from the Tibetan Plateau south into the Andaman Sea. The Salween flows primarily within southwest China and eastern Myanmar (Burma), with a short section forming the border of Burma and Thailand. Throughout most of its course, it runs swiftly through rugged mountain canyons. Despite the river's great length, only the last 90 km (56 mi) are navigable, where it forms a modest estuary and delta at Mawlamyine. The river is known by various names along its course, including the Thanlwin in Burma and the Nu Jiang in China. The commonly used spelling "Salween" is an anglicisation of the Burmese name dating from 19th-century British maps.