The parent stock of what is called the Indo-European family of nations. They lived probably in Bactria, i.e. between the river Oxus and the Hindu-koosh mountains. The Aryan family of languages include the Persian and Hindû with all the European except Basque, Turkish, Hungarian, and Finnic. Sometimes called the IndoEuropean, sometimes the Indo-Germanic, and sometimes the Japetic.
Sanskrit, Zend, Latin, Greek, and Celtic are, of course, included.