Thus, on the slopes of hill Gradina that dominates with the harbour examples of hand-made prehistoric pottery were found, that along with remains of walls, show that a prehistoric settlement was there.
Also, on the hill os St.Roco a prehistoric remains, where a church was latter built, can be found. On the cost of Trpanj, on the hill Gradina , Roman conquerors found a settlement of the Iliric tribe Plerejas .
On the top of the same hill, in late Antique, at the beggining of the turbulent sixth century during Gots´ domination over Dalmatiathe Byzanthine emperor Justinian struggles to regain the cost, and builds numerous fortresses along with Trpanj's Gradina in order to secure the sea way along the coast.
The inhabitants of Trpanj were first to persist on the usage of Croatian language in commercial correspondence.
At that time high aristocracy and citizens who had Italian language as a role model looked down on the wider usage of the common people language.
The persistancy of Trpanjs inhabitants had reverberation in the entire Dalmatia, which evoked so strong a rage in Autonomists that they even gave them a mocking name "teribili farauni" which was on pride of every inhabitant of Trpanj.