The Roman conquest of the island began in AD 43, leading to the establishment of the Roman province known in Latin as Britannia. The Romans never successfully conquered the whole island, building Hadrian's Wall as a boundary with Caledonia, which covered roughly the territory of modern Scotland, although the whole of the boundary marked by Hadrian's Wall lies within modern-day Northern England. A southern part of what is now Scotland was occupied by the Romans for about 20 years in the mid-2nd century AD, keeping in place the Picts to the north of the Antonine Wall. People living in the Roman province of Britannia were called Britanni, or Britons. Ireland, inhabited by the Scoti, was never invaded and was called Hibernia. Thule, an island "six days' sail north of Britain, and [...] near the frozen sea", possibly Iceland, was also never invaded by the Romans.