Complex sentence: In Bangladesh, a few gaur were thought to occur in the Chittagong Hill Tracts, Sylhet, and Mymensingh areas in the early 1980s, but none had been seen in Pablakhali Wildlife Sanctuary situated in the Hill Tracts since the early 1970s.
Split into simpler sentences: In Bangladesh, a few gaur were thought to occur in the Chittagong Hill Tracts, Sylhet, and Mymensingh areas in the early 1980s. But none had been seen in Pablakhali Wildlife Sanctuary situated in the Hill Tracts since the early 1970s.