The Tagin tribe is one of the major tribe of Arunachal Pradesh, India, which is a member of the larger designation of Tani Tribes, the descedents of Abo Tani. Mostly Tagins are in Upper Subansiri district but are also found to be dispersed among the adjoining districts especially in West Siang.
The most important festival of the Tagins, Si-Donyi, involves the veneration of the earth(si) and the sun(donyi). Si-Donyi is celebrated from 4th to 7th January every year. It is celebrated as New Year. Where the Nyibu (local priest) presides over and performs all the rituals with chanting of Uuyu Benam (celestial chantings). And sacrifice of Mithuns for peace and prosperity in the community as whole.