They are not some anonymous “a tribe in India”, they are the War-Khasi. Speaking as a former anthro student and as a reference librarian, I am beyond sick of posts (and articles, and emails, and museum displays) like this that present the work of a people without actually naming the people. It’s erasure, it’s reducing the great works of a culture to an Ozymandias-esque curiosity for foreigners to consume rather than an accomplishment that should help bring awareness of that culture’s existence.
They are the War-Khasi, a division of the Khasi, a people who call themselves Hynñiew Trep. They live in Meghalaya, and they have been building these bridges in the town of Cherrapunji for longer than anyone knows. They are not anonymous.
