During the last two thousand years BC, during the Bronze Age, the first fortifications and stone buildings were erected by Liburian peoples. They could serve as shelter to the population from the surrounding villages in case of danger, and some of them may have been permanent settlements where the local rulers had their seats. In addition, they oversaw important cattle and trade routes leading to Velebit and further to Lika via Paklenica or Rujan. Some of them served to oversee navigation. They are now destroyed, but ring-shaped mounds up to several meters in height can still be seen in some places. In the immediate vicinity of the fortifications, casket heaps - deposits of large round stone under which former rulers were buried in casket made of stone tablets - have been found. Most of them have been dug out and the graves robbed, but they are still visible, as in the area of the village of Ljubotić above Tribanj-Kruščica.