The Romans began their conquest of southern Gaul (later known as the Provincia) in 125 BC. In 118 BC they founded the colony of Narbo Martius (Narbonne, the Mediterranean city nearest to inland Toulouse) and made contact with the Tolosates, noted for their wealth and the position of their capital for trade with the Atlantic. Tolosa allied with the Romans, who established a fort on the plain north of the city (a key position near the border of independent Aquitania) but otherwise left Tolosa semi-independent.