The earliest settlements on the Indian sub-continent were the Dravidian people who comprised the Harrapan civilization. Little is known about them because much of their artifacts are under water and their rather complicated language has not yet been deciphered. It is known that they had a very advanced civilization with streets laid out on a grid system, some large palatial mansions with showers and flush toilets that emptied into a central sewer system, and apparently large scale agriculture, although the nature of that agriculture cannot be known with certainty. It is known that the civilization grew rapidly; and that they deforested large areas of land to plant more crops. This deforestation ultimately worked against them as the soil was eroded, and the civilization went into decline.
The Dravidian were very gradually replaced by an Indo-European people known as the Aryans, a word meaning "noble people" in their language. Although they occasionally fought with the Dravidians and among each other, they did not conquer them. Aryans were primarily a pastoral people who raised sheep and cattle although they did engage in some small scale farming. Wealth was measured in terms of cattle; however horses were highly prized and used not only to pull carts and wagons but also to pull chariots with devastating effect. Horses did not breed well in India, so they had to be imported.
The Aryans had no written language, but preserved their myths and literary works orally in a sacred language called Sanskrit. Their everyday language was known as Prakit, which later became modern Hindi, Bengali, and Urdu. They later compiled a large collection of hymns to their gods known as the Rig Veda.
The Aryans had no central government, but were organized into herding communities ruled by a king known as the Rajah. They often fought bitterly with each other.
Socially, their society was highly stratified based on ones occupation and role in life. This stratification was the forerunner of the Caste system which dominated Indian social and religious life for many years. There is some argument that class distinction was based on skin color rather than wealth. They recognized four major classes, or Varna, ("color"): The Brahmins, (Priests); kshatriyas, (warriors and aristocrats); vaishas, (farmers, artisans and merchants); and shudras, (landless peasants and serfs.) Later, a fifth class was added, the "untouchables," to apply to those who performed dirty or unpleasant tasks, such as handling the dead, or butchering animals.