Zambezi km from the sea the Zambezi receives the drainage of Lake Malawi through the Shire River. On approaching the Indian Ocean, the river splits up into a delta. Each of the four primary distributaries, Kongone, Luabo and Timbwe, is obstructed by a sand bar. A more northerly branch, called the Chinde mouth, has a minimum depth at low water of 2 m at the entrance and 4 m further in, and is the branch used for navigation. 100 km further north is a river called the Quelimane, after the town at its mouth. This stream, which is silting up, receives
Zambezi term "Sena River" ("Rio de Sena"), a reference to the Swahili (and later Portuguese) upriver trade station at Sena. In 1752, the Zambezi delta, under the name "Rivers of Sena" ("Rios de Sena") formed a colonial administrative district of Portuguese Mozambique. But common usage of "Zambezi" led eventually to a royal decree in 1858 officially renaming the district "Zambézia". The Zambezi region was known to medieval geographers as the Empire of Monomotapa, and the course of the river, as well as the position of lakes Ngami and Nyasa, were given broadly accurately in early maps. These were probably constructed from