The Chief Ministers of the Northeast Indian states were:
(1). Arunachal Pradesh - Pema Khandu
(2). Assam - Himanta Biswa Sarma
(3). Manipur - N. Biren Singh
(4). Meghalaya - Conrad Sangma
(5). Mizoram - Zoramthanga
(6). Nagaland - Neiphiu Rio
(7). Sikkim - Prem Singh Tamang (also known as P. S. Golay)
(8). Tripura - Biplab Kumar Deb
It's important to note that political leadership can change with time, and there may have been changes since my knowledge cutoff date