Roman roads in Britannia the military road from Carlisle to Corbridge, was built under the Emperor Trajan (ruled 98–117 AD) along the line of the future Hadrian's Wall, which was constructed by his successor Hadrian in 122–132 AD. Scotland ("Caledonia"), including England north of Hadrian's Wall, remained mostly outside the boundaries of "Britannia" province, as the Romans never succeeded in subjugating the entire island, despite a serious effort to do so by governor Gnaeus Julius Agricola in 82–84 AD. However, the Romans maintained a system of forts in the lowland region ca. 80–220 AD to control the indigenous population beyond Hadrian's Wall and annexed
Scotland during the Roman Empire 367. The era saw the emergence of the earliest historical accounts of the natives. The most enduring legacies of Rome, however, were Christianity and literacy, both of which arrived indirectly via Irish missionaries. Scotland had been inhabited for thousands of years before the Romans arrived. However, it is only during the Greco-Roman period that Scotland is recorded in writing. The work "On the Cosmos" by Aristotle or Pseudo-Aristotle mentions two "very large" islands called Albion (Great Britain) and Ierne (Ireland). The Greek explorer and geographer Pytheas visited Britain sometime between 322 and 285 and may have circumnavigated the mainland, which