For a long period of time, scholars thought the Indus-Sarasvati civilization was destroyed abruptly by invaders from the northwest known as Aryans (ārya meaning “noble” in the Sanskrit language).
In the present, researchers favor a different picture of ancient Indian history and they have nearly come to the conclusion that there was not an Aryan invasion. They showed that dramatic climate changes, caused by a major tectonic catastrophe changing the rivers course, was the reason of the decline of the Indus-Sarasvati cities.
Particularly, it caused the drying up of what was once the largest river of India, the Sarasvati, with flourished numerous towns and villages along its banks. Presently the dry river bed runs through the Thar Desert.
The drying up of the Sarasvati had some great consequences. Just imagine the Mississippi running dry instead of constantly flooding. What havoc this would cause! The death of the Sarasvati forced the population to migrate to the country’s more fertile parts, particularly south into Central India and Tamilnadu and east toward the Ganges River.
So why is this important for the history of Yoga? The Sarasvati is the most celebrated river in the Rig-Veda. It is created in an archaic form of Sanskrit, the language in which most Yoga scriptures are written, and was transmitted by mouth word for numerous generations. It is related to other languages such as French, Latin, Greek, German, Spanish, and English.
If the Sarasvati River really dried up around 1900 B.C., the Rig-Veda must have been earlier than that date. So the composers of this hymns collection must have been contemporaneous with the Indus civilization, flourished between 3000-1900 B.C. Indeed, astronomical references in the Rig-Veda suggest at least some of its hymns were created in the third or fourth millennium B.C.
Therefore, the Sanskrit-speaking Aryans did not come from outside India in order to destroy the Indus-Sarasvati civilization. What was their relationship with the Indus-Sarasvati people? Although opinions still differ, there is an understanding that the Indus-Sarasvati and the Aryans people were the same. There is nothing in the Rig-Veda to suggest anything else.