They lost their trade colonies in the Western Adriatic coast due to invasion of the Umbri and the Gauls, caused by expansion of the Etruscan union in the basin of Po river. The 5th century BC saw Greek colonization in the south Adriatic, and final Liburnian retreat to Liburnia was caused by military and political activities of Dionysius the Elder of Syracuse in the 4th century BC. Liburnia was strongly held, but Greek colonization reached Liburnian strategic possessions in the central Adriatic, Issa (on the island of Vis) and Pharos (Starigrad, Hvar), a colony of the Greeks from Paros. Celtic invasion from the west bypassed Liburnia in the 4th century BC, but their northern neighbors the Iapodes were under considerably more pressure. The Liburnians took the opportunity to spread their territory to the Kvarner archipelago and the eastern coast of Istria to the river Raša, previously held by Iapodes, thus making the Histri their new neighbors to the west. On the basis of ancient records, the Iapodes inhabited the coast between Albona (Labin) and Lopsica (Sv. Juraj, south from Senj) and island Curycta (Krk) to the end of the 4th century BC. Material remains from the Early Iron Age in that region have alternately shown Histrian provenance, not necessarily Liburnian, but often ascribed to the Liburnians from the 4th century BC to the age of Roman conquest. Although archaeology of the region has not strictly confirmed the earlier presence of Iapodian material culture the group's presence and strong influence on the region is evident. They surely broke to Kvarner in the 20s of the 3rd century BC and the border between Iapodia and Liburnia was the river Telavius (Žrnovnica, Velebit Channel). It’s not certain how long they ruled these coasts (some propose until the 1st century BC) and when exactly they retreated to their main historical lands. Borders of Liburnia didn’t change until its conflict with Dalmatae in 51 BC, when the Liburnians lost their city Promona (Tepljuh, Drniš) in the south and probably some lands around Krka river. By that time the Romans were already engaged in centuries long wars against Liburnian neighbors, Histri, Dalmatae and other Illyrians. Roman Liburnia When Roman force ended the independence of their naval force in 33 BC, the Liburnians lost their freedom and Liburnia became a part of the Roman province of Dalmatia, but marginal in a military sense. Burnum on the Krka