The Rig Veda 1200-900 BC

The Rig-Veda is a collection of over 1,000 hymns, which contain the mythology of the Hindu gods, and is considered to be one of the foundations of the Hindu religion. While the Rig is the oldest of the Vedas, there are three other Vedas. There is the Sama Veda, which is the "knowledge of chants" or a number of basic hymns recited at sacrifices.  There is also the Yajur Veda or "knowledge of rites" which serve basically as a "how to make sacrifices" book.  The final Veda is the Athara Veda, this Veda represents the knowledge given by Athara who was a sage.  These Vedas were passed on orally for many generations.  When they were written down, they were first written in Vedic, an early form of Sanskrit. Then around 300 B.C. the Vedas were written down in the form we have them today.
Back to "Indus Valley Civilization" ChronologyThe Rig Veda was written by the Aryans who entered the Indus Valey toward the end of theHarappan Civilization.  They wrote this Veda between 1300 and 1000 BC, during the period of the Aryan Migrations.  However, there may be possible Harappan influences on these works.  This is because the Vedas were actually being developed before the Aryans arrived around 2000 B.C.
Although there are many Vedas written, the most important is the Rig, which contains over 1,000 hymns directed to the gods.  The content of these hymns includes praises, blessings, sacrifices, and curses.  These hymns are the major way in which the Aryan people praised their gods.  The subject of the hymns is the personification of the powers of nature.  The hymns are written in poetic form:
"This light hath come, of all the lights the fairest,
The brilliant brightness hath been born, far-shining,
Urged on to prompt the sun-god's shining power.
Night and Morning clash not, nor yet do linger."  (Bloomfield 30)

As you can see, this is very poetic language.  This can be chanted,  creating a worshipful mood in a person. When you chant these words, you are transported into another state of mind.  In fact, this and other hymns were probably chanted by the Aryan people at one of their religious ceremonies.
The theology of the Vedas was later developed in the Upanishads. At the end of the Rig and all of the Vedas, the Hindu Brahmins added a summary of the philosophy of the Veda. The Upanishads became the basis of Hinduism.  For the Hindu person, they serve as a summary of all of the knowledge of the Veda as well as a commentary on them.
The religion that sprang forth from the Vedas helped shape Indian society.  For example, the Rig Veda and Vedic literature were used in the development of the caste system.  The Rig Veda describes how the god Purusha sacrificed himself to himself. Each of the pieces of his body developed into a different portion of society. His mouth became the Brahmin or priests; his arms became the Kshatriyas or warriors; his thighs became the Vaisya or merchants, farmers, herders and artisans; and the feet became the Sudra or slaves and servants. Thus, while each part of society had its own role, it was still and single body.