Trans-Karakoram Tract
By 1892, the British settled on the policy that their preferred boundary for Kashmir was the "Indus watershed", i.e., the water-parting from which waters flow into the Indus river system on one side and into the Tarim basin on the other. In the north, this water-parting was along the Karakoram range. In the east, it was more complicated because the Chip Chap River, Galwan River and the Chang Chenmo River flow into the Indus whereas the Karakash River flows into the Tarim basin. A boundary alignment along this water-parting was defined by the Viceroy Lord Elgin and communicated to London. The British government in due course proposed it to China via its envoy Sir Claude MacDonald in 1899. This boundary, which came to be called the Macartney–MacDonald Line, ceded to China the Aksai Chin plains in the northeast, and the Trans-Karakoram Tract in the north. In return, the British wanted China to cede its 'shadowy suzerainty' on Hunza.