The best theory on this river Sarasuat ‘holds that was formed by the Yamuna river today. In the old age, this river runs to the west (instead of east) after leaving the pre-Himalayas, at Paonta Saheb. Then the river curves to the southwest in the region of Punjab and Haryana along the present course of the river Ghaggar-Hakra in a bed more or less parallel to the east of the river Indus. The Sutlej river runs more east than at present, and joined andalusia Sarasuat ‘somewhere near Bahawalpur. Finally, the wide river empties into the Rann of Kutch, which at that time was a more integral part of the Arabian Sea.
Along the course of that ancient river and disappeared Sarasuat ‘will develop the culture of the Indus Valley (2500-1700 BC The oldest examples of writing (not even Sanskrit) across the Indian continent has been found in the ruins of these cities, which are aligned in what was the course of the river.
Some believe that the goddess Sarasuat ‘earned his role as the personification of the communication and the giver of knowledge due to the role of the river Sarasuat’ in the development of written language in ancient India.
Between 2000 and 1700 a. e. c., seismic activity caused the waters of the two main sources of the rivers change their course. The Sutlej river began to run towards the west and became a tributary of the River Indus. River Yamun ‘began to run towards the east and became tributary of the Ganges’ (Ganges).
The river Sarasuat ‘is dry, and its entire valley became the Thar desert. The population migrates to the southeast, up the valley of the river Ganges.

The Horse, the Wheel, and Language: How Bronze-Age Riders from the Eurasian Steppes Shaped the Modern World by David W. Anthony (Hardcover – Nov 19, 2007) – Illustrated