Indians date their history from the Vedic Period which scholars place in the second and first millennia BC continuing up to the 6th century BC, based on literary evidence. This is the period when the Vedas, the oldest and holiest books of Hinduism, were compiled. The earliest archaeological traces are from 7000 BC in Mehrgarh, which grew to be the "Indus Valley Civilization". By 3300 BC, this civilization had well-planned towns and well-laid roads, but gave no evidence of weapons or fortifications. This declined and disintegrated around 1900 BC, possibly due to drought and geological disturbances. Most historians say that the Vedic people, or Aryans, were later migrants, who encountered a civilization in decline and perhaps hastened that decline. According to this view, the Vedic people eventually occupied most of North India, while the descendants of the Indus Valley cultures moved south and gave rise to the Dravidian culture. The minority view challenges this Aryan Migration theory, claiming that the Indus Valley people were in fact the ones who compiled the Vedas.
The Vedic civilization influences India to this day. Present-day Hinduism traces its roots to the Vedas, but is also heavily influenced by literature that came afterwards, like the Upanishads, the Puranas, the great epics — Ramayana and Mahabharata, and the Bhagavad Gita. By tradition, these books claim to only expand and distill the knowledge that is already present in the Vedas. Some rituals of Hinduism took shape during that period. Most North-Indian languages come from Sanskrit, the language of the Vedas, and are classified as part of the Indo-European group of languages. In the 1st millennium BC, various schools of thought in philosophy developed, enriching Hinduism greatly. Most of them claimed to derive from the Vedas. However, three of these schools - Sikhism , Buddhism and Jainism - questioned the authority of the Vedas and they are now recognized as separate religions.
