In the 4th century BCE, the first invasion of Celts is recorded. They brought the technique of the pottery wheel, new types of fibulas and different bronze and iron belts. They only passed on their way to Greece, so their influence in Bosnia and Herzegovina is negligible. Celtic migrations displaced many Illyrian tribes from their former lands, but some Celtic and Illyrian tribes mixed. Concrete historical evidence for this period is scarce, but overall it appears the region was populated by a number of different peoples speaking distinct languages.