Complex sentence: The Byerley Turk was reportedly a dark brown horse with but was not Oriental or Arabian (which may have been Akhal-Teke) he was larger framed although Turk horses possessed large eyes, long and high set on neck and high carriage of the tail.
Split into simpler sentences: The Byerley Turk was reportedly a dark brown horse but was not Oriental or Arabian. He had a large frame and Turk horses possessed large eyes, long and high set on neck and high carriage of the tail.