Trilj is a city in the Cetina region, located on the southeastern edge of Sinj Field. The position on the direction of the communication between the coast and inland, the natural features of the river Cetina and the nearby mountainous landscape, contributed to the continuity of life in Trilj region from the earliest prehistoric times.
In the area of Trilj there are many archaeological findings dating way back to Mesolithic. The first ethnic group that inhabited this area are the Illyrian tribe Delmati. Delmati people lived in a hill forts along the communication lines that connected their capital Delminium with Adriatic coast. Hundred and fifty years of fierce fighting against the Romans (165 BC.- 9. AD) ended in defeat of Delmati people, after which Romans built legionary fortress Tilurium on the hill above Trilj.
At the top of the hill of Gardun, just 1 km south of Trilj, remains of legionary fortress at Tilurium can be found. Tilurium guarded the entrance to the Cetina valley from the south and the approach to the provincial capital at Salona.