Koteka is a kind of tribal dress worn by certain indigenous tribes living in Papua, which is an island shared by Indonesia and Papua New Guinea. The Koteka Tribal Assembly is a gathering of these tribal people to discuss issues related to their community and culture.
It's like when you and your family have a meeting to talk about important things, except this meeting is with different families from different tribes. They wear their special traditional dress, called Koteka, which covers their private parts. The meeting is all about talking and sharing ideas about how to live better and make their community stronger.