Koyu is a Sub-District in the East Siang District of Arunachal Pradesh. As par Census 2011 information the sub-district code of Koyu is 01648. There are about 15 sub-districts in East Siang and Koyu is one of them. Bilat, Boleng, Kebang, Kora, Mebo, Namsing, Nari, New Seren, Pangin, Pasighat, Rebo Perging, Riga, Ruksin, Sille Oyan etc. are other sub-districts in East Siang.There are about 12 villages in Koyu sub-district.