Tyrone, former county, Ulster Province, central Northern Ireland; Omagh was the county town. Tyrone comprised peaks of the Sperrin Mountains in the north and the valleys of the Mourne and Blackwater rivers. The region was ruled by the O'Neill family from the 5th century to the early 17th century, when it came under the domination of the English. Tyrone ceased to exist as an administrative unit in 1973.