The Pahari people, also called Pahadi, Parbati, Khāsā, or Chhetri, are an Indo-Aryan ethnic group of the Himalayas living in Nepal, India, and Pakistan. In Nepal, the Pahari constituted the single largest ethnic group at about 20,000,000, or three-fifths of the Nepalese population through the 1990s. They also constituted the majority population of the Indian States of Himachal Pradesh and Uttarakhand. Most Indo-Aryan Pahari, however, identify as members of constituent subgroups and castes within the larger Pahari community such as Chhetri and Thakuri.
The name Pahari derives from pahar, meaning "hill", and corresponds to the Himalayan Hill Region which the Pahari inhabit. The term Pahari may indicate contrast to the Indo-Aryan Madhesi ("midlander") of the Terai, groups of Tibetan origin, and indigenous communities such as the Newar and Tharu of the Himalaya. Pahari may also contrast geography alone, encompassing even non-Indo-Aryan ethnicities and language groups such as the Pahari Newar community and their Newar dialect.

Main article: History of Nepal
The Pahari are historically ancient, having been mentioned by the authors Pliny and Herodotus and figuring in India's epic poem, the Mahābhārata. References to Brahmins and Kshatriyas are found in Banawali (Tantric texts) on Nepal, in whose ancient setting Kathmandu was still a lake. These texts also contain references to Lord Krishna, himself considered a Kshatriya prince, who came with his cow herding group and remained around the Kathmandu Valley. Kathmandu was ruled by cow herding Gopal Bamsa long before other castes settled the area. The four Narayan temples around the valley were established by these Vaishnava people.
Before Nepal was united as a nation under the Shah dynasty (1768–2008), smaller kingdoms in the region were ruled by kings of various ethnic and caste groups. The ancient name of this Himalayan region was Khas-des. Most populous among the people of this mid-mountainous area were the Khas people, also mentioned in the histories of India and China. The Khas people, Indo-European Aryan mountain dwellers, spread to dominate the hills of Central Himalaya and played important role in the history of the region, establishing many independent dynasties in early medieval times. The Khas people had an empire, the Kaśa Kingdom, which included Kashmir, part of Tibet, and Western Nepal (Karnali Zone).
In the early modern history of Nepal, Pahari Chhetris played a key role in the unification of Nepal, providing the backbone of the Rajput Gorkhali army of the mid-18th century. During the monarchy, Chhetris and Bahuns continued to dominate the ranks of the Nepalese Army, police, Nepalese government administration, and even one regiment of the Indian Army. Under the pre-democratic constitution and institutions of the state, Chhetri culture and language also dominated multiethnic Nepal to the disadvantage and exclusion of many Nepalese minorities and indigenous peoples. The desire for increased self-determination among these minorities and indigenous peoples was one of the central issues in the Nepalese Civil War and subsequent democratic movement.
During the Shah Dynasty, the Pahari began to settle the Terai region, theretofore dominated by Madhesi peoples. Politically, socially, and economically dominant over the Madhesi under the conservative system of the monarchy, the Pahari community in the Terai purchased, or otherwise got hold of large landholdings. Together with traditional Tharu landlords, they constitute the upper level of the economic hierarchy, which in the rural parts of the Terai is determined to a large extent by the distribution and the value of agriculturally productive land. The poor are the landless, or near landless, Terai Dalits, including the Musahar and Chamar, as well as the traditional fishermen, the Mallaah, and some of the hill Dalits. In particular the Musahars rarely get other work than hard farm labor. During and after the Nepalese Civil War, Paharis faced a violent backlash by the marginalized Madhesi community including ransoming, murder, and land dispossession by armed Maoist groups such as the Janatantrik Terai Mukti Morcha (JTMM) seeking Madhesi independence.

Religion and castes
Further information: Hinduism in Nepal
Most Nepalese Paharis are Hindus, with the exception of the shamanistic and oracular Matwali ("drinking") Khasa Chhetris. Hindu Paharis are generally more conscious of their caste (varna, jati) and status than their indigenous neighbors, especially those Paharis living in rural Nepal. However, as a result of extensive historical contact with non-Hindu Nepalese, the Pahari caste structure is less orthodox and less complex than the traditional four-fold system in the plains to the south. The Pahari system is generally two-fold, consisting of the higher "clean" or "twice-born" castes and the lower "unclean" or "polluting" castes. The "twice-born" include the Bahun (Brahmin) and Chhetri (Kshatriya) castes.
Chhetris as a caste comprise many subgroups, including Khasa (clans from Khas) and Thakuri (aristocratic clans). The Khasa subgroups are widespread in the Karnali Zone.