The history of Brittany begins with settlement beginning in prehistoric times, beginning around 700 000 BCE. The neolithic era, which began around 5000 BCE, is characterised in the region by the development of an important megalithic art found in sites such as the cairn of Barnenez, the cairn of Gavrinis, the table of the Merchants of Locmariaquer or the alignments of Carnac. In the course of its protohistory which began around the middle of the third century BCE, a subsoil rich in tin allowed the development of an industry in bronze objects, which led to commercial routes for export to other regions of Europe. It was inhabited by Gallic peoples including the Veneti and the Namnetes in the first centuries BCE before these territories were conquered by Julius Caesar in 57 BCE, and progressively Romanized.