Collective name of a group of Indo-European tribes that migrated from central and northern Europe (or possibly Asia Minor or the southern steppes—the precise location is uncertain) around the start of the second millennium bce, possibly due to ecological or climatic changes and the need to seek new pastures for their animals. Whether the tribes belonged to a single ethnic group is unclear, but even if they did, the Indo-Aryan languages they spoke, of which Sanskrit is a descendant, may have ceased to be associated with any defined racial type at an early age. Two main routes of migration were followed: one to western Europe, and the other to Iran (which derives its name from the word Āryan), and India. In India, the Āryans colonized the northern part of the country and according to some accounts subjugated the indigenous Dravidian peoples, who came to comprise the lowest of the four castes of Āryan society, although this claim is controversial. The religious beliefs of the Āryans are recorded in ancient Hindu scriptures written in Sanskrit known as the vedas, and involved the worship (pūjā) of a plurality of divine beings, many of whom are personifications of natural phenomena such as the sun, moon, and atmospheric phenomena like lightning, thunder, and storms. In Buddhism, the term Ārya is used in the sense of ‘noble’ or ‘venerable’, and takes on a specific meaning in connection with the ‘noble ones’ who have attained various stages of spiritual progress. See ārya-mārga; Four Noble Truths.