Complex sentence: Montgomery was previously known as Black Hole for the creek that flows through it and the post office established in 1836 bearing that name and it was also known as Clinton Mills, again named for the post office.
Split into simpler sentences: Montgomery was previously known as Black Hole for the creek that flows through it; the post office was established in 1836 bearing that name. It was also known as Clinton Mills, again named for the post office.