Gaul was a historical region of Western Europe during the Iron Age that was inhabited by Celtic tribes, encompassing present day France, Luxembourg, Belgium, most of Switzerland, and parts of Northern Italy, Netherlands, and Germany, particularly the west bank of the Rhine. It covered an area of 494,000 km2 (191,000 sq mi). According to the testimony of Julius Caesar, Gaul was divided into three parts: Gallia Celtica, Belgica, and Aquitania.
Archaeologically, the Gauls were bearers of the La Tène culture, which extended across all of Gaul, as well as east to Raetia, Noricum, Pannonia, and southwestern Germania during the 5th to 1st centuries BC.
During the 2nd and 1st centuries BC, Gaul fell under Roman rule: Gallia Cisalpina was conquered in 203 BC and Gallia Narbonensis in 123 BC. Gaul was invaded after 120 BC by the Cimbri and the Teutons, who were in turn defeated by the Romans by 103 BC. Julius Caesar finally subdued the remaining parts of Gaul in his campaigns of 58 to 51 BC.