Behind us to the north we have flat, level land on the southern bank of the Tsangpo. We have mounted only 315 feet from the river to the Kore-la, where the height is 15,292 feet or 4662 metres asl. And from the pass there is a headlong descent to the Kali Gandak, an affluent of the Ganges. By means of a canal cut through the Kore-la the Brahmaputra might be turned into the Ganges. Northern India needs water for irrigation, but the gain would perhaps be small, for the Brahmaputra in Assam would be as much diminished as the Ganges was increased. Tibet would be opened. A new road would be opened for the invasion of India from the north, and therefore on the whole it is perhaps best for all parties concerned to leave things as they are. But the changes here indicated will some time come to pass without artificial aid, for the tentacles of the Kali Gandak are eating back northwards into the mountains much more quickly than the Tsangpo is eroding its valley. Some time or other, perhaps in a hundred thousand years, the Ganges system will have extended its tentacles to the bank of the Tsangpo, and then will be formed a bifurcation which, in the course of time, will bring about a total revolution in the proportions of the two rivers and their drainage areas."