Nobody knows exactly who the first people settling the area around Ilirska Bistrica were. They left no inscriptions, books or frescoes. Yet, on almost every hill above Ilirska Bistrica, Šembije and further on towards Šilentabor, on St Catherine, Jasen and Draga, one can find huge cyclopean walls, remains of mighty hillforts, large settlements and extensive graveyards dating to late Bronze Age and early Iron Age.

The places around Ilirska Bistrica bustled back in those times when the main trade routes led through here. The strategic importance and rich natural resources of the area enabled a thriving little civilization that flourished up to the Roman invasion in late 1^st century BC.

Apart from the megalithic walls, hillforts and remains of settlements, somebody left behind a mysterious petroglyph cut into a speleothem in the cave by the Trnovo spring (The Iapydes Cave). It could be Illyrian, but it might also be the first depiction of Perun, the Slavic god of thunder.