The Karachays or Karachais (Karachay-Balkar: къарачайлыла, romanized: qaraçaylıla or таулула, tawlula, 'mountaineers') are a North Caucasian-Turkic ethnic group primarily located in their ancestral lands in Karachay–Cherkess Republic, a republic of Russia in the North Caucasus. They and the Balkars share a common origin, culture, and language.

The names used by the Karachay-Balkar to refer to themselves (enonym) and the names assigned to them by neighboring Caucasian peoples in their own languages (exonym) are presented in the following table.

Karachays and Balkars are listed as among the peoples indigenous to the North Caucasus. According to Balkar historian, ethnographer and archaeologist Ismail Miziev [ru] who was a specialist in the field of North Caucasian studies, the theories on the origins of the Karachays and the neighboring Balkars is among "one of the most difficult problems in Caucasian studies," due to the fact that they are "a Turk-speaking people occupying the most Alpine regions of Central Caucasus, living in an environment of Caucasian and Iranian (Ossetian) languages." Many scientists and historians have made attempts to study the issue, but "the complexity of a problem lead to numerous hypotheses, often contradicting each other." He concluded that "Balkarians and Karachais are among the most ancient nationalities of Caucasus. The roots of their history and culture are intimately intertwined with the history and culture of many Caucasian peoples, as well as numerous Turk nationalities, from Yakutia to Turkey, from Azerbaijan to Tatarstan, from the Kumik and Nogai to the Altai and Hakass."

Ankara University's professor Ufuk Tavkul, another specialist, locates that the ethnogenesis of Karachays-Balkars and Kumyks inside the Caucasus, not outside; he then succinctly describes the ethnogenesis of peoples of the Caucasus, including the Karachays and Balkars, thus:

In the first millennium before Christ diverse groups representing the ancestors of the Abkhaz/Adyghe, Ossetian and Karachay-Balkar people lived in the Caucasus, who contributed to varying degrees to the emergence of these peoples. From the 7th century BC Kimmerian, Scythian, Sarmatian, Alan, Hun, Bulghar Turk, Avar, Khazar, Pecheneg, Kipchak, etc. groups invaded the Caucasus and settled there, causing a radical change in the ethnic map of the Central Caucasus.
By assimilating the local Caucasian people of Caucasid anthropological features who had brought to life the Koban culture of the Bronze Age, the Ossetians of an Iranian tongue and the Turkic-speaking Karachay-Balkars emerged in the Middle Caucasus. The Ossetian and Karachay-Balkar people and cultures were certainly fundamentally influenced by the Caucasian substratum belonging to the Koban culture (Betrozov 2009: 227)

— "About Karachay-Balkar people: Ethnogenesis", in Sipos & Tavkul (2015), Karachay-Balkar folksongs, p. 44.

Other research by Boulygina et al. (2020) shows Karachays' genetic connection to the pre-historic Koban culture. A recent genetic study states the following: "Balkars and Karachays belong to the Caucasian anthropological type. According to the results of craniology, somatology, odontology, and dermatoglyphics, the native (Caucasian) origin of the Balkars and Karachays and their kinship with the representatives of neighboring ethnic groups and a minor role of the Central Asian component in their ethnogenesis were concluded."

The state of Alania was established prior to the Mongol invasions and had its capital in Maghas, which some authors locate in Arkhyz, the mountains currently inhabited by the Karachay, while others place it in either what is now modern Ingushetia or North Ossetia. In the 14th century, Alania was destroyed by Timur and the decimated population dispersed into the mountains.