In present days, the regional drainage configuration is very different from how it originally was. River systems were eastward flowing, with the Indus as an exception, before the continental collision started. At present, most rivers are flowing south to southeast. The Salween, Yom, Mekong and Red river are drastically bent around the northeastern tip of the Indian continent. By further examining and studying the deformation patterns in these river basins, a two-phase deformation model in the East Himalayas is verified. This shows that rivers are reliable indicators of crustal strain and useful in reconstructing regional tectonic history. Moreover, the Indus and the Ganges river originally flowed parallel to the regional thrust on the Asian continent, but are now flowing perpendicular to it. They crossed the thrust and extended onto the Indian continent. This is conformable to the above-mentioned model proposed by Burbank (1992). Since tectonic uplift has significantly slowed down nowadays compared to when the collision has just started, the present day Indian-Asian collision region is dominated by erosional processes. Rivers like the Indus and Ganges, which originated from the Lhasa block, are therefore able to flow as transverse rivers and reach beyond the proximal part of the Himalayas mountain range.