Tibet: A History, Sam Van Schaik, Yale University Press, 2011, ISBN 978-0-300-15404-7, ... The Tanguts were a people from the same ethnic background as the Tibetans, but unlike the Azha and the Sumpa, who had been subsumed by the Tibetan empire and by Tibetan culture, the Tanguts lived far enough to the north to have avoided this fate ...
