In fact, the site chosen for Aquileia was about 6 km from where an estimated 12,000 Celtic Taurisci nomads had attempted to settle in 183 BC. However, since the 13th century BC, the site, on the river and at the head of the Adriatic, had also been of commercial importance as the end of the Baltic amber (sucinum) trade. It is, therefore, theoretically not unlikely that Aquileia had been a Gallic oppidum even before the coming of the Romans. However, few Celtic artifacts have been discovered from 500 BC to the Roman arrival.
Source: Aquileia – Wikipedia