Tribal people with sophisticated metalworking skills but no written language, the Celts kept expanding their European territory from central Europe toward the west. By the fifth century B.C., they were dominant in Gaul (modern France), England, Ireland, much of Scotland, and parts of Spain. By the third century B.C., the Celts spread through the Balkans. They made beautiful golden jewelry and harness ornaments. In some places, the Celts built large forts atop hills and fought Roman legions as the empire absorbed Europe. Later, the Celts clashed with the barbarians that overran the territory through the early centuries A.D.