Kojur (or Kojoor) District is a district in Nowshahr County, Mazandaran Province, Iran. At the 2006 census, its population was 14,203, in 4,028 families.The District has no cities. The District has three rural districts (dehestan): Panjak-e Rastaq Rural District, Tavabe-e Kojur Rural District, and Zanus Rastaq Rural District.
The historical district of Kojur covers roughly a quadrangle (about 55 km by 40 km) bounded by the Caspian Sea on the north, the Čālus River on the west, Nur valley on the south, and Suledeh valley on the east. Its exact contours have always been a subject for debate owing to recurrent renaming, administrative changes, and inaccurate cartography.
A close scrutiny of historical sources points to the following constituent parts:
1- The core of Kojur consists of the surroundings of the river Pul (also called Kojur), which rises from the main Alborz massif and flows west-northwest for some 40 km before it joins the Čālus River. This secluded basin is bounded on three sides by offshoots of the Alborz range: on the south stands the great Varavašt as its highest peak (4,008 m) within the Nur ridge, on the dry southern face of which lies the Nur district; on the north, a low, lateral chain separates the Pul valley from the Caspian coastline; and on the east lies Qalʿa Gardan with its highest point at 2,623 m.
2- Across the latter mountain runs an out-of-the-way high valley, which also bears the name of Kojur, with a river (not to be mistaken with the abovementioned Pul/Kojur river) running some 35 km longitudinally into the Caspian Sea.
3- Some 15 km further east runs the parallel valley of Galandrud, which opens onto the littoral plain some 5 km before reaching the Caspian Sea.
4- North of the mountainous interior mentioned above, there is an associated coastal area, which stretches some 50 km along the Caspian seashore, from the Chalous (Chalus) River to Alamdeh (renamed Ruyān in the 1990s) and Suledeh/Suldeh (presently, Nur city). In the coastal area the mountains advance toward the coastline, leaving a very narrow littoral plain, less than 3 km wide for the most part, which is crossed by several northward-flowing streams other than the Kojur and Galandrud rivers mentioned above.