The Indo-Gangetic plains are drained by several fan and interfan rivers fringing the margin of the outer Himalaya. These fan and interfan river systems are distinctly different from each other in terms of hydrology and sediment transport and generate typical alluvial architecture below the plains. The Siwalik sequences stretching all along the Himalaya from Potwar Plateau in the west to the Tista valley in the east are considered as the most obvious ancient analogue for the Gangetic plains. This paper reviews the geomorphic setting, fluvial processes and sedimentation pattern in the Gangetic plains and draws parallels with the Siwalik Group.