When we open a history book used in our schools today, we find that it invariably begins with a description of the Indus Valley Civilization. It usually starts off with an account of the discovery of the two major sites Harappa and Mohenjodaro, followed by a brief description of what was found there. We will also be told how this civilization went into decline and finally disappeared by 1500 BCE (3500 BP). The main cause of this disappearance, the reader is then informed, was the invasion of India by nomadic tribes from Central Asia called the Aryans. According to this account, these invading Aryans, who are said to have entered India through the passages in the northwest, fought and overcame the inhabitants of the Indus Valley and established themselves over much of North India. They are then said to have composed their literature, the most important of which is the Rig Veda. This history of India begins in earnest with the records of the Aryans following their invasion. This in essence is the account of ancient history found not only in school books, but also in such authoritative sources as the Encyclopedia Britannica.
The modern science of molecular genetics has demolished the whole notion of the Aryans. Archaeology also has disproved the idea of an Aryan invasion. In addition to political and racial ideas that were given a linguistic garb, some religious beliefs also played a part in creating the Aryan Invasion Theory. In the 19th century Europe many students were taught the Biblical superstition that the world was created in its present form with all its life forms on 23rd October 4004 BCE. European scholars steeped in this belief, could not accept that Indian history and civilization went much further back in time. So they distorted and misinterpreted records to fit their own limited worldview.
In recent years, recognizing that the Aryan Invasion Theory has been disproved, some scholars are proposing something they are calling the Aryan Migration Theory. This, too, is no more valid. All the old contradictions remain and some new ones arise as well. These both are rejected for the same reasons.