Let's look into the actual ethnography. Humphrey's primary ethnographic research for the paper Graeber cites as definitive was based on her research of the Lhomi of the Arun Valley in northern Nepal near the Tibetan border. Of the Lohmi, Humphrey writes (1985, pp.54-55): "Before the virtual closure of the Tibetan border by the early 1970's which followed the Chinese invasion, the Lhomi engaged in three kinds of barter." These are: