Despite all, Kinthup was still dedicated to his task, and after a few months he asked permission to make a pilgrimage, and used his leave to cut and mark the logs. He did not throw them in the water yet - it was eighteen months since he had left India, and he realized that no one would be looking for the logs any more. So Kinthup returned to the monastery, some time later asked for permission to make a pilgrimage again, and went to Lhasa, where he had a fellow Sikkimese bring a letter to the survey authorities to tell about his fate, and announce when he would be throwing the logs into the river. Kinthup returned to the monastery, and on his next leave threw the logs into the river as announced. Only then he returned to India, but there disappointment awaited him. His letter had not reached India, and his report of his travels was not believed.
Kinthup left the survey and became a tailor. Only many years later did geographers realize that his reports and his story were completely correct - and that the Tsangpo and the Brahmaputra were indeed the same river.