From as early as 3000 BC Egyptian Pharaohs referred to northern Ethiopia as the Land of Punt, rich in precious resources including gold, myrrh and ivory. The region was in contact with southern Arabia by around 2000 BC, with settlers bringing Semitic languages and stone-building techniques. Early in the 1st century AD a prosperous and advanced civilization arose in the northern highlands, centred on Aksum. Christianity reached Aksum in the 4th century AD when King Ezana was converted by Frumentius of Tyre. At its height in the 6th century AD the Aksumite empire controlled much of the Red Sea coast and traded with the Mediterranean powers, as well as Persia and India.