The River Moyola or Moyola River stretches for approximately 27 miles from the Sperrin Mountains to Lough Neagh. The Moyola starts a small river (3-5m) for the first few miles of its length and proceeds to expand to a medium sized river (5-20m) and then to a large river (20m+) for its last couple of miles before Lough Neagh. In ancient times, the River Moyola was known as the 'Bior', and served as the border between the Airgiallan kingdoms of Fir Li and Ui Tuirtri.