The area is intimately associated with the heartland of the Delmatae and the area's strategic importance is emphasised by the citing of the legionary fortress at Tilurium (Gardun), just above today's city of Trilj, which guards the entrance to the valley from the south and the approach to the provincial capital at Salona.
Vrlika was first mentioned in written sources in 1069, as the seat of Cetin County (Cetinska županija) - the old Croatian county, which included the towns of: Glavaš, Prozor, Sinj, Trilj, Stolac, Gradac, Nutjak, Tugare and Poljic parish (Poljička župa).