What is Indo-Brahma theory ? Explain.

Arguments Against the Theory : The theory of Indo-Brahma has not been accepted universally. It has been challenged on the following grounds :

Firstly, the concept of such a mighty river Indo-Brahma flowing all along the longitudinal extent of the Himalayas is not possible. The occurrence of Siwalik alluvial deposits might have been formed by successive deposition of alluvial fans by the rivers flowing down the Himalayan slopes.

Secondly, the evidence furnished by the depositional history in the Ganga delta and in the Assam does not prove this concept as the deposits in the gap lying between the two projections of the peninsular block-Rajmahal hills and Shillong plateau, have been composed of thick alluvium older than that suggested by the Indo-Brahma theory.
Thirdly, the evidences of Tipan sandstorm of Assam has not been accepted by this theory.