The correct answer is Arunachal Pradesh. The Nyishi tribe is the largest ethnic group in Arunachal Pradesh, residing primarily in the central part of the state. The Nyishi people are known for their distinctive culture, language, and traditions. They are mainly concentrated in the districts of Papum Pare, East Kameng, Kurung Kumey, Kra Daadi, and Lower Subansiri in Arunachal Pradesh.