against the Welsh. Palisades have been found as far apart as the borders of China and Manchuria and of Manchuria and Korea, and the outskirts of the Roman dominions beyond the Danube and the Rhine. Spartianus, in his Life of Hadrian, describes the palisade erected by that Emperor in the trans-Danubian section of the Roman Frontier, and the researches of the German explorers, who in recent years have laid bare the traces of that remarkable barricade from end to end, have revealed the existence of split oak trunks, nine feet high, driven into a deep ditch, and held together by stout transverse beams.
The palisade or rampart or wall of ancient history was, however, the commonest illustration of a type of Frontier that was concerned less with delimitation than with defence. When the Chinese built the Great Wall of China, when Hadrian and Antoninus Pius and Severus raised the double line of fortification between the Firths of Clyde and Forth, and between the Solway and the mouth of the Tyne, when the Flavian Emperors built the Pfahlgraben and other ramparts or walls between the Rhine and the Danube, when the successors of Alexander raised a similar barrier in the country to the east of the Caspian—one and all were not thinking so much of rounding off the territories of conquests of the Empire as they were of protecting its Frontiers in the best manner against the terrible and ever-swelling menace of the barbarians. Consequently the wall or barrier was sometimes erected upon the administrative Frontier, and sometimes far in advance of it. Though Hadrian's wall was for centuries the effective Frontier of the Roman dominion in Britain, the Romans yet to some
- Vit. Hadriani, 12.