The history of Portuguese wine has been influenced by Portugal's relative isolationism in the world's wine market, with the one notable exception of its relationship with the British. Wine has been made in Portugal since at least 2000 BC when the Tartessians planted vines in the Sado and Tagus valleys. By the 10th century BC, the Phoenicians had arrived and introduced new grape varieties and winemaking techniques to the area. Up until this point, viticulture was mostly centered on the southern coastal areas of Portugal. In later centuries, the Ancient Greeks, Celts and Romans would do much to spread viticulture and winemaking further north.