preferred to call the area Saintonge and themselves Santones – and then the Romans in the 1st century BC. Saintonge offered better living and working conditions than the northern area (Aunis) thanks to the large valleys of the river Charente and its two principal tributaries, the Seugne and the Boutonne. The huge Gironde Estuary of the Seudre allowed direct contact with the more advanced civilisation of the Roman Empire to the south, via the Garonne valley. Transport was largely on the waterways, even after the Romans had built their more advanced – and more expensive – roads. Before the Roman conquest around the middle of the 1st century AD, the Celts had a stronghold over the northern shores of the Gulf of Santones. They had even colonised some of the islands in the gulf, which today are part of the Marais () de Rochefort. The Santones had worked laboriously to perfect a technique of saltwater extraction, and their ancient production sites were put right on the shoreline. These are ("salt sites"). These small-scale production sites were particularly numerous in the north of the Gulf of Santones, equally along the coastline, in the deep estuaries, and all around the islands (notably the Île d'Albe). The salt sites were quickly abandoned after the Roman conquest, because the new colonists brought with them a better-performing and more-productive technique for producing salt. Nevertheless, the Romans preferred to have their first salt marshes in the south, notably at Marennes, and on the banks of the river Seudre. Salt production, which before had been driven by profit, could be done faster around the Gironde, which became an important arterial river for the transport of goods to and from the southern provinces of the Roman Empire. During the first three centuries of the Gallo-Roman period, the Romans were especially keen to colonise the area between the coastline of Aunis and the ancient sylve d'Argenson ("Forest of Argenson"), taking lands latterly in Santone hands. The new colonists, somewhat turning their backs to the sea, set up their – large farms of some dozens of acres, predating the towns themselves – at Ardillières, Le Thou, Ballon, and Thairé. All these sites left numerous archaeological finds: at Ballon, the remains of a Gallo-Roman villa have been found; at Ardillières, tombs with Gallo-Roman objects have been recovered; at Thou, a Gallo-Roman villa and some coins were discovered in the 19th century.