This hat of woven rattan and bamboo, which is believed to have been collected in the region in the early 20th century, is believed to have been worn by a Nyishi (also spelt Nishi) warrior. (The Nyishi are one of the tribes of Arunachal Pradesh in India.)
The men of the tribe wore hair buns at the front of their heads. The shape of this hat allows for that. The cane fin that curves over the hat is believed to emulate the beak of a hornbill.
A hat of related form is illustrated in van Cutsem (2005, p. 108).
The example here has fine patina, and is in perfection condition.
van Cutsem, A., A World of Head Ornaments: Africa, Asia Oceania, America, Skira, 2005.