Zanskar is a subdistrict or tehsil of the Kargil district, which lies in the eastern half of the Indian state of Jammu and Kashmir. The administrative centre is Padum. Zanskar, together with the neighbouring region of Ladakh, formerly belonged to Guge or Western Tibet.

Zanskar covers an area of some 7,000square kilometres (2,700square miles), at a height of between 3,500 and 7,000metres (11,500–23,000feet). It consists of the country lying along the two main branches of the Zanskar river. The first, the Doda, has its source near the Pensi-la (4,400m) (14,450ft) mountain-pass, and then flows south-eastwards along the main valley leading towards Padum, the capital of Zanskar. The second branch is formed by two main tributaries known as Kargyag river, with its source near the Shingo La (5,091m) (16,703ft), and Tsarap river, with its source near the Baralacha-La. These two rivers unite below the village of Purne to form the Lungnak river (also known as the Lingti or Tsarap). The Lungnak river then flows north-westwards along a narrow gorge towards Zanskar's central valley (known locally as gzhung khor), where it unites with the Doda river to form the Zanskar river.

The Zanskar river then takes a north-eastern course until it joins the Indus in Ladakh. High mountain ridges lie on both sides of the Doda and Lingti–kargyag valleys, which run north-west to south-east. To the south-west is the Great Himalayan Range which separates Zanskar from the Kisthwar and Chamba basins. To the north-east lies the Zanskar Range, which separates Zanskar from Ladakh. The only outlet for the whole Zanskar hydrographic system is thus the Zanskar river, which cuts a deep and narrow gorge through the Zanskar range.

These topographical features explain why access to Zanskar is difficult from all sides. Communication with the neighbouring Himalayan areas is maintained across mountain passes or along the Zanskar river when frozen. The easiest approach leads from Kargil through the Suru valley and over the Pensi La. It is along this track that in 1979 the first and only road in Zanskar was built to connect Padum with the main road from Srinagar into Ladakh. One of the first Tibetologists to spend an extended period in the region was Alexander Csoma de Koros, who spent over a year living in the region in 1823. After being integrated into the newly formed state of India in 1947, Zanskar and the neighboring region of Ladakh were both declared restricted areas and only opened to foreigners only in 1974. The first colour film of life in Zanskar was shot in 1958 by an expedition of three British housewives[39].

Zanskar's population is small, the April 2006 medical census records a population of 13,849 people. The medical census is the most accurate indicator of population as it collects birth, death, and census information from Zangskar's 22 medical aid centers. Roughly 95% of the inhabitants practice Tibetan Buddhism, while the remainder are Sunni Muslims, whose ancestors settled in Padum and its environs in the 19th century. The majority of Zanskaris are of mixed Tibetan and Indo-European origins; notably Dard and Mon. The latter are in fact ethnically Dard, but "Mon" is used in order to distinguish them from later Dard settlers.

The population lives mainly in scattered small villages, the largest being the capital Padum, with nearly 700 inhabitants. Most of the villages are located in the valleys of the Zanskar river and its two main tributaries. Given the isolation of this region, the inhabitants tend towards self-sufficiency, and until recently lived in almost complete autarky. External trade has, however, always been necessary for the acquisition of goods such as tools, jewellery, or religious artefacts.

The Zanskaris' main occupations are cattle-rearing and farming of land that they almost always own. Cultivable land is scarce, and restricted to alluvial fans and terraces, cultivated fields being rarely found above an altitude of 4,000 metres. The Zanskaris have developed a system of intensive arable agriculture and complex irrigation to produce enough food in these conditions. The scarcity of cultivable land has also resulted in a tendency towards a stable, zero-growth population. An efficient birth-control system in Zanskar has historically been achieved by the common practice of polyandrous marriage, in which several brothers are married to the same wife, and the widespread adoption of a celibate religious life. A high infant mortality rate also contributes to population stability.

The first traces of human activity in Zanskar seem to go back as far as the Bronze Age. Petroglyphs attributed to that period suggest that their creators were hunters on the steppes of central Asia, living between Kazakhstan and China. It is suspected that an Indo-European population known as the Mon might then have lived in this region, before mixing with or being replaced by the next settlers, the Dards. Early Buddhism coming from Kashmir spread its influence in Zanskar, possibly as early as 200 BCE. The earliest monuments date from the Kushan period. After this eastward propagation of Buddhism, Zanskar and a large part of the Western Himalaya were overrun in the 7th century by the Tibetans, who imposed their then animistic Bön religion.

Buddhism regained its influence over Zanskar in the 8th century when Tibet was also converted to this religion. Between the 10th and 11th centuries, two Royal Houses were founded in Zanskar, and the monasteries of Karsha and Phugtal (see picture) were built. Until the 15th century Zanskar existed as a more or less independent Buddhist Kingdom ruled by between two and four related royal families. Since the 15th century, Zanskar has been subordinate to Ladakh, sharing its fortunes and misfortunes. In 1822 a coalition of Kulu, Lahoul, and Kinnaur invaded Zanskar, plundering the country and destroying the Royal palace at Padum.

In the mid-20th century, border conflicts between India, Pakistan, and China caused Ladakh and Zanskar to be closed to foreigners. During these wars Ladakh lost two thirds of its original territory, losing Baltistan to Pakistan and the Aksai Chin to China. Ladakh and Zanskar, despite a tumultuous history of internal wars and external aggressions, have never lost their cultural and religious heritage since the 8th century. Thanks to its adherence to the Indian Union, this is also one of the rare regions in the Himalaya where traditional Tibetan culture, society, and buildings survived the Chinese Cultural Revolution. In the last twenty years, the opening of a road and the massive influx of tourists and researchers have brought many changes to the traditional social organisation of Zanskar. In 2007 the valley suffered its third year of a desert locust infestation with many villages losing their crops. The response of the monasteries was to carry out Puja ( prayer ) to get rid of them whilst the government was advocating the use of insectisides which the Buddhists were reluctant to use, but in some cases were forced to try with as yet undocumented success. In 2008 it was reported that the Locusts had left the central Zanskar plains.