Early Civilizations, Aryan Settlement and the Vedic Age
In about 1500 bc the Aryans, a nomadic people from Central Asia, settled in the upper reaches of the Indus, Yamuna, and Gangetic plains. They spoke a language from the Indo-European family and worshiped gods similar to those of later-era Greeks and northern Europeans. The Aryans are particularly important to Indian history because they originated the earliest forms of the sacred Vedas (orally transmitted texts of hymns of devotion to the gods, manuals of sacrifice for their worship, and philosophical speculation). By 800 bc the Aryans ruled in most of northern India, occasionally fighting among themselves or with the peoples of the land they were settling. There is no evidence of what happened to the people displaced by the Aryans. In fact they may not have been displaced at all but instead may have been incorporated in Aryan culture or left alone in the hills of northern India.
The Vedas, which are considered the core of Hinduism, provide much information about the Aryans. The major gods of the Vedic peoples remain in the pantheon of present-day Hindus; the core rituals surrounding birth, marriage, and death retain their Vedic form. The Vedas also contain the seeds of great epic literature and philosophical traditions in India. One example is the Mahabharata, an epic of the battle between two noble families that dates from 400 bc but probably draws on tales composed much earlier. Another example is the Upanishads, philosophical treatises that were composed between the 8th and the 5th centuries bc.
As the Aryans slowly settled into agriculture and moved southeast through the Gangetic Plain, they relinquished their seminomadic style of living and changed their social and political structures. Instead of a warrior leading a tribe, with a tribal assembly as a check on his power, an Aryan chieftain ruled over territory, with its society divided into hereditary groups. This structure became the beginning of the caste system, which has survived in India until the present day. The four castes that emerged from this era were the Brahmans (priests), the Kshatriyas (warriors and rulers), the Vaisyas (merchants, farmers, and traders), and the Sudras (artisans, laborers, and servants).