The earliest epigraphically attested reference to the word "Aryan" occurs in the 6th-century BC Behistun inscription
, which describes itself to have been composed "in Aryan (arya
) [language or script]" (§ 70). The "Aryan" in this context means "Iranian
The term Aryan has generally been used to describe the Proto-Indo-Iranian language root *arya which was the ethnonym the Indo-Iranians adopted to describe Aryans. Its cognate in Sanskrit is the word ārya (Devanāgarī: आर्य), in origin an ethnic self-designation, in Classical Sanskrit meaning "honourable, respectable, noble". The Old Persian cognate ariya- (Old Persian cuneiform: 𐎠𐎼𐎡𐎹) is the ancestor of the modern name of Iran and ethnonym for the Iranian people.
In the 18th century, the most ancient known Indo-European languages were those of the ancient Indo-Iranians. The word Aryan was therefore adopted to refer not only to the Indo-Iranian peoples, but also to native Indo-European speakers as a whole, including the Romans, Greeks, and the Germans. It was soon recognised that Balts, Celts, and Slavs also belonged to the same group. It was argued that all of these languages originated from a common root – now known as Proto-Indo-European – spoken by an ancient people who were thought of as ancestors of the European, Iranian, and Indo-Aryan peoples.
This usage was common among knowledgeable authors writing in the late 19th and early 20th centuries. An example of this usage appears in The Outline of History, a bestselling 1920 work by H. G. Wells. In that influential volume, Wells used the term in the plural ("the Aryan peoples"), but he was a staunch opponent of the racist and politically motivated exploitation of the singular term ("the Aryan people") by earlier authors like Houston Stewart Chamberlain (see below) and was careful either to avoid the generic singular, though he did refer now and again in the singular to some specific "Aryan people" (e.g., the Scythians). In 1922, in A Short History of the World, Wells depicted a highly diverse group of various "Aryan peoples" learning "methods of civilization" and then, by means of different uncoordinated movements that Wells believed were part of a larger dialectical rhythm of conflict between settled civilizations and nomadic invaders that also encompassed Aegean and Mongol peoples inter alia, "subjugat[ing]" – "in form" but not in "ideas and methods" – "the whole ancient world, Semitic, Aegean and Egyptian alike".
However, in a climate of burgeoning racism it proved difficult to maintain such nuanced distinctions. Even Max Mueller, a linguist who wrote in 1888 that "an ethnologist who speaks of Aryan race, Aryan blood, Aryan eyes and hair, is as great a sinner as a linguist who speaks of a dolichocephalic dictionary or a brachycephalic grammar", was on occasion guilty of using the term "Aryan race".
In the 1944 edition of Rand McNally's World Atlas, the Aryan race is depicted as one of the ten major racial groupings of mankind. The science fiction author Poul Anderson, an anti-racist libertarian of Scandinavian ancestry, in his many works, consistently used the term Aryan as a synonym for "Indo-Europeans".
The use of "Aryan" as a synonym for Indo -European may occasionally appear in material that is based on historic scholarship. Thus, a 1989 article in Scientific American, Colin Renfrew uses the term "Aryan" as a synonym for "Indo-European".
The term Indo-Aryan is still commonly used to describe the Indic half of the Indo-Iranian languages, i.e., the family that includes Sanskrit and modern languages such as Hindi-Urdu, Bengali, Punjabi, Gujarati, Romani, Kashmiri, Sinhalese and Marathi.