There are many accounts of the origin of the city, but the most likely is a version by Tamilla Khalilova. Since the 7th century, conquest of the South Caucasus by Arabs began. According to historical data the Arabs reached a territory of present Qusar Rayon. According to the historians version name of the river is originated from Arabian Al-Qausar. In translation from the Quran into English “Al Qausar – in translation means a river of abundance, that is a heaven river, water of which is whiter than milk and sweeter than honey. Its fragrance is nicer than musk and birds with beautiful long necks like necks of camels fly around it.” The settlement got its name from the river – Qusar. Modern historians believe that the name Qusar derives from khisar.
In 1836, Mikhail Lermontov visited Qusar, where he met with scientist-philosopher Haji Ali-efendi. There he heard “Ashiq Qarib” dastan from an eminent ahiq Lazgi Ahmad; he later wrote his famous work “Ashiq Qarib” based on its motifs. A home-museum of the poet is reserved in the city with a memorial plate, inscribed with the famous lines of Lermontov:
In 1938, Qusar settlement acquired a city status.
The city is located not far from Bazarduzu, Shahdagh Mountains and a border with Russia. The mountain river Qusarchay, in honor of which the city acquired its name, flows in Qusar. There is also an artificial lake, Fialka.
Qusar is located in a zone of subtropical climate and the northern part of the rayon is in zone of mild climate. But because of the heights above the sea level and proximity of the mountains winter is always cold here, and summer is not hot. Temperature of air can change more than 15 degrees during a day. For instance, in summer incessant days-long rains can begin after hot weather.
According to “The Caucasian calendar” of 1916, there lived 1203 people, primarily Russian, in the territory of Qusar. In 1926, there were 120 Mountain Jews, a number which had increased to 241 by 1939.
According to a census of 1959, at least 7366 people lived in Qusar. According to a census of 1979, population of the city consisted of 12225 people, and in 1989 it reached 14230.
97% of the population consists of Lezgins.
The economy of Qusar is partially agricultural, partially tourist based, with some industries in operation. There are tinned food, milk and asphalt factories in the city.
Qusar is home to Shahdag Winter Complex, the largest ski resort in Azerbaijan.
Local history museum was established in 1982. There are 3000 exhibits in the museum.
The Qusar State Art Gallery was opened in 1986. 101 works of Azerbaijani artists are on display in the gallery.
In 1998, the State Drama Theatre of Lezgins was opened in Qusar.
Qusar has plenty of parks and gardens, mostly well maintained. The Nariman Narimanov Park is the most scenic park in the town.
The city has one professional football team, Shahdag Qusar, currently competing in the second-flight of Azerbaijani football, the Azerbaijan First Division.
Qusar's urban transport system is mostly managed by the Ministry of Transportation.
In 2008, 6 secondary schools, one of which functions in Azerbaijani and 5 in Russian language, were operating in the city. There are also two state run preschools and one private preschool, Panda School, as well as Azerbaijan State Pedagogical College, which trains future teachers of Azerbaijani, English, and elementary school. As of 2016 there are three language schools in the city. The most popular one, Apex English Language School, has been operating in Qusar since 2013.Makhmud Abilov, Soviet Major General, who fought in the Soviet-Georgian War and World War II
Rafael Amirbekov, footballer, Baku FC's player
Rahid Amirguliyev, footballer, Khazar Lankaran's player
Farida Azizova, taekwondo practitioner
Timofey Borshev, People's Commissar of International Affairs of the Turkmen SSR (1938-1942).
Gavriil Ilizarov, Soviet physician, known for inventing the Ilizarov apparatus for lengthening limb bones and for his eponymous surgery.
Sedaget Kerimova, Lezgin writer, poet and journalist