The Gaels emerged into the clear historical record during the classical era, with ogham inscriptions and quite detailed references in Greco-Roman ethnography (most notably by Ptolemy). The Roman Empire conquered most of Britain in the 1st century, but did not conquer Ireland or the far north of Britain. The Gaels had relations with the Roman world, mostly through trade. Roman jewelry and coins have been found at several Irish royal sites, for example. Gaels, known to the Romans as "Scoti", also carried out raids on Roman Britain, together with the Picts. These raids increased in the 4th century, as Roman rule in Britain began to collapse. This era was also marked by a Gaelic presence in Britain; in what is today Wales, the Déisi founded the Kingdom of Dyfed and the Uí Liatháin founded Brycheiniog. There was also some Irish settlement in Cornwall. To the north, the Dál Riata are held to have established a territory in Argyll and the Hebrides.