From about the fourth century b.c. Rome had a long-standing alliance with the Greek colony of Massilia (Marseilles) whose territory was constantly raided by southern Gallic tribes; these incursions called for military intervention from the Romans from the middle of the second century, culminating in a series of successful campaigns, the enlargement of Massilia's territory, the founding of the colony of Aquae Sextiae (Aix, 30 miles north of Marseilles), and the annexation of southern Gaul in 121 b.c. after the defeat of the Allobroges and Arverni. The province stretched from the Pyrenees up to Tolosa (Toulouse), then the frontier skirted the Cevennes to the Jura Mountains and the south-west corner of Lacus Lemannus (Lake Geneva); then it came in a south-south-easterly line to the Mediterranean coasts, by the Maritime Alps. It formed a very valuable corridor from Italy to Spain, and through it ran the Via Domitia beyond the Rhone; in 118 b.c. Narbo Martius (Narbonne) was founded, and so flourishing a Roman civilization grew up that Pliny later described it as ‘Italia verius quam provincia’.