The site is located in the south-westem slopes of the Koytendag mountains (the Kugitang range), at the south-westem extreme of the Gissar range of the Pamir-Alay mountain system. Generally, it lies in the middle and upper mountainous belts at elevations of 900-3139m above sea level, which it reaches at Ayrybaba (the highest peak of Turkmenistan). There are a substantial number of waterbodies: karst lakes and caves (Kattakul, Khurdzhumkul, Garlyk and others), freshwater springs (Bulakly and Koyten) and hydrogen sulphate wells (Khodzhakainar, Khodzhapil and Bazartepe). Some watercourses originate in snowfields, located at altitudes of about 3000 m. The main water source is the Koytendarya river. The climate depends on altitude, changing from arid and hot to temperate and cold with annual precipitation of up to 350mm. The soils are serozyems (grey earth). The flora is composed of 982 species. Juniperus (or archa) forests with Thragacanthus communities are widespread (1700-2800 m), in which Astracanta sp. and steppe grasses are also present. Seasonal grazing and cattle reariing are carried out here, as well as arable farming to a lesser degree. Most of the population (up to 50 000 people) lives in the Koytendarya valley; the main villages are Garlyk, Koyten, Khodzhapil, Gorshun.
The proposed WH site includes the following protected areas:
1. Koytendag State Nature Reserve (27 139 ha)
2. Karlyuk State Nature Sanctuary (40 000 ha)
3. Khojapilskiy State Nature Sanctuary (31 635 ha)
4. Khojaburjibelendskiy State Nature Sanctuary (17 592 ha)
5.Khojakaraulskiy State Nature Sanctuary (6 000 ha)
The total area of the proposed site is 122 366 ha.
Koytendag is famous for its unique caves and other geological features (marble onyx), as well as its archa forest and species of rare plants and animals such as the blind cave loach (Nemacheilus starostini) which inhabits underground lakes in the karstic caves. Notable elements of the flora include Juniperus seravschanica, tulip (Tulipa ingens), almond (Amygdalus spinosissima), Cleome gordjaginii, and Ungernia victoris. Some woods are composed of oriental plane, jujube and pistachio. The beautiful mountains and caves are supplemented by the presence of markhor and Barbary falcon (Falco pelegrinoides). See threat status below.
The nominated site represents the main periods of Earth development, including the illustration of ancient life, significant geological processes in Earth surface forms development, essential geomorphological and physical-geographical particularities of relief. The site is composed of rocks of the Precambrian, Paleozoic, Mesozoic, and Cainozoic Eras rich with ancient fossils of Molluscs, Brachiopods, and dinosaurs - including dinosaur footprint trails, etc. At the base of the Koytendag mountains there are igneous rocks, testament to ancient volcanism, as well as tectonic faults and canyons.
The unique geological formations of Koytendag cave complex have no equal in Eurasia for the diversity of geological processes that formed them, as well as for the beauty of their geological phenomena.
Endemic fish are represented by Kugitang Blind Loach Nemacheilus starostini (IUCN Red List status: Vulnurable VU), and a relict mollusc species Kainar Cerith Melanoides kainarensis occurs. Globally and near threatened mammal species include Tajik Markhor Capra falconeri, (EN), Tien Shan Brown Bear Ursus arctos isabellinus, Turkestan Lynx Lynx lynx isabellinus (NT), Persian Leopard Panthera pardus saxicolor (NT), which may already be locally extinct; Afghan Urial Ovis orientalis cycloceros (VU), European Free-tailed Bat Tadarida teniotis and others.
The site qualifies as an Important Bird Area (IBA) and holds the complex of bird species typical for Turan deserts and the Kopetdag-Khorassan and Pamir-Alay mountain systems. Species distribution is restricted by three biomes: the Eurasian high mountains - Alpine and Tibetan (two nesting species were found in the breeding period); Irano-Turanian mountains (six nesting species were found) and Sino-Himalayan temperate forests (three breeding species were found). Special attention should be paid to globally threatened and near threatened species such as the Cinereous Vulture Aegypius monachus (NT) and Saker Falcon Falco cherrug (EN) and other birds of prey whose breeding populations are supported within this IBA: Lammergeier Gypaetus barbatus, Short-toed Snake-eagle Circaetus gallicus, Golden Eagle Aquila chrysaetos, Eurasian Eagle-owl Bubo bubo, Peregrine Falcon Falco peregrinus, probably, Barbary Falcon Falco pelegrinoides and Lesser Kestrel Falco naumanni (NT). The avifauna consists of 158 species, including 55 residents, 67 breeding migrants, 22 wintering and migratory species and 14 occasional migrants (vagrant).
As an isolated mountain area, Koytendag represents an integral natural complex. The site is unique for featuring desert habitat and also a physical mountain barrier which prevented the invasion of elements of flora and fauna from other mountain systems. Koytendag State Nature Reserve and its Sanctuaries are governmental property and are under the structure of the Ministry of Nature Protection of Turkmenistan.
Koytendag is most similar to other mountainous reserves in Central Asia, such as Chatkal in Uzbekistan, Aksu-Dzhabagly in Kazakhstan and Sary-Chelek in Kyrgyzstan, but unlike them has a number of highly distinctive geological features.