The Draa (Shilha Berber: asif n Dra, Arabic وادى درعة wādī Darʿah, also spelled Dra or Drâa, in older sources mostly Darha or Dara), is Morocco's longest river, 1,100 kilometres (680 mi). It is formed by the confluence of the Dadès River and Imini River. It flows from the High Atlas mountains south-(east)ward to Tagounit and from Tagounit mostly westwards to the Atlantic Ocean somewhat north of Tan-Tan. Most of the year the part of the Draa after Tagounit falls dry.
The water from the Draa is used to irrigate palm groves and small horticulture along the river. The inhabitants of the Draa are called in Arabic Drawa, in Shilha Idrawiyn, the most famous Drawi (singular of Drawa) undoubtedly being Sultan Mohammed ash-Sheikh (1490–1557). Outside of the Draa region this name is mostly used to refer to the dark skinned people of Draa which make up the largest portion of its inhabitants.
In the first half of the 20th century the Draa lowest course marked the boundary between the French protectorate of Morocco and the area under Spanish rule.
About 225,000 people live in the valley of the Draa, which measures 23,000 square kilometres (8,900 sq mi). The valley corresponds with the province of Zagora, created in 1997, in the Souss-Massa-Drâa region. In the province there are 23 villages and two towns: Zagora and Agdz. The village of Tamegroute, near Zagora, is well known for its Zawiya.
The valley contains the Fezouata formations, which are Burgess shale-type deposits dating to the Lower Ordovician, filling an important preservational window between the common Cambrian lagerstätten and the Late Ordovician Soom shale. In the fossilized fauna were numerous organisms previously thought to have died out after the mid-Cambrian.