Scotland during the Roman Empire of the geography of Scotland had extended to the "Hebudes" (The Hebrides), "Dumna" (probably the Outer Hebrides), the Caledonian Forest, and the Caledonians. Ptolemy, possibly drawing on earlier sources of information as well as more contemporary accounts from the Agricolan invasion, identified 18 tribes in Scotland in his "Geography", but many of the names are obscure. His information becomes much less reliable in the north and west, suggesting early Roman knowledge of these area was confined to observations from the sea. Famously, his coördinates place most of Scotland north of Hadrian's Wall bent at a right angle, stretching due eastward
Vestiges of the Gallo-Roman wall, Grenoble to the construction of the wall in the end of the 3rd century AD, the Gallic city of Cularo (Grenoble) was surrounded by a fence and a ditch. During the Roman Peace (Pax Romana) period (27 BC to 180 AD), the walls were not guarded. In the 3rd century, the city was weakened by the invasion of barbarians, so the Gallo-Romans built a surrounding wall, under the rule of the Emperor Diocletian. The wall surrounding Cularo covered 9 hectares of land and had two main gates. At the time, the city had an approximate population of 2000 inhabitants. Cularo appears