The Cambridge History of India, Vol. I: Ancient India v1.c15.63

v1.c15.63

Where the Brahmaputra bends southward round the foot of the Gāro hills the valley of Assam opens to the plain of Bengal. Across that plain westward, where the Ganges makes a similar southward bend round the Rājmahāl hills, Bengal merges with the great plain of Hindustān, which extends westward and north-westward along the foot of the Himālayas for some seven hundred miles to the point where the Jumna, westernmost of the Gangetic tributaries, leaves its mountain valley. Hindustān begins with a breadth of about a hundred miles between the Rājmahāl hills and the northern mountains, spreads gradually to a breadth of two hundred miles from the foot hills of the Himālayas to the first rise of the Central Indian hills, and then narrows again to a hundred miles where it merges with the Punjab plain between the Ridge of Delhi and the Himālayas. The great river Jumna-Ganges streams southward from the mountains across the head of the plain to Delhi, and then gradually bends south-eastward and eastward along that edge of the plain which is remote from the mountains, as though it were pinned against the foot of the Central hills by the impact of the successive great tributaries from the north. Three of these tributaries are the Upper Ganges itself, whose confluence is at Allahābād, and the Gogrā and the Gandak which enter above Patna. The Jumna-Ganges receives from the south the Chambal and Son, long rivers but comparatively poor in water.