Thank you, Pamela, for your quick consideration of my post. Ironically this morning I was re-shelving a bunch of research books and noticed a small one which has a photograph on it's front cover that did get me encouraged. The book is
Patterns on Textiles of the Ethnic Groups in Northeast of Vietnam, published in 1997 by the Cultures of Nationalities Publishing House, Hanoi. The author is Diep Trung Binh. Just as you and Martin speculated this piece may be from Vietnam. Again, however, the opening on the right is not is not the same as the tops featured in the book which appear to be slipped on over the head. The one is in the book is from the Phu La People belonging to the Tibeto-Burman languare group with a reported population of only 7,500 living in areas of Lao Cai, Ha Giang, Son La , and Lai Chau Provinces of Vietnam.
The jacket itself belongs to a collector who purchases mainly in Beijing.
The book was revised by Barbara Cohen. You can find an image of the cover on Amazon:
http://www.amazon.com/s/ref=nb_sb_noss? ... of+Vietnam Hopefully this lead will further the quest.
Many thanks,
Pam Najdowski