Complex sentence: New York State has recognized the Shinnecock, based at Shinnecock Reservation near Southampton and the Unkechaugi, whose Poospatuck Reservation at Mastic is the smallest Indian reservation in the state.
Split into simpler sentences: New York State has recognized the Shinnecock, based at Shinnecock Reservation near Southampton and the Unkechaugi. The latter's Poospatuck Reservation at Mastic is the smallest Indian reservation in the state.