 Complete the following phrase:  One of the earliest treaties regarding the boundaries in the western sector was signed in 1842. Ladakh was conquered a few years earlier by the armies of Raja Gulab Singh Dogra under the suzerainty of the Sikh Empire. Following an unsuccessful campaign into Tibet in 1840, Gulab Singh and the Tibetans signed a treaty, agreeing to stick to the old, established frontiers, which were left unspecified. The 