In our days the various tribes of the Highland and Lowland populations live in peaceful union under one and the same government. But during several centuries Scotland was the theatre of the most sanguinary contests between the Celtic Highlanders and the Teutonic Lowlanders. The former, who were animated with an inveterate hatred of the Lowlanders, continually made hostile incursions into the Lowlands, and, after burning and ravaging the country, retired with cattle and other booty to their mountains, whither they knew well the Lowlanders durst not follow them. The exasperation and hatred of the Highlanders were not entirely without foundation. In ancient times they had been sole masters in Scotland, from the Cheviot Hills to the Orkneys and the Shetland Isles, and from the Atlantic Ocean to the North Sea; and they had retained this mastery even long after their kinsmen, the Britons in England, had been compelled to yield to the Romans and Anglo-Saxons. The celebrated Roman commander, Agricola, had, it is true, in the first century after the birth of Christ, made his way so far into the Lowlands that, as a defence against the Highlanders—the much-dreaded Caledonians, or Picts—he constructed a wall with a deep ditch before it, from the Firth of Forth to that of Clyde, in the low tract through which the Glasgow Canal has since been conducted. The Romans even extended their conquests farther northwards, as far as Burghead on the Moray Firth, to which place they formed regular high roads. But they were not able to defend themselves against the persevering attacks of the Caledonians, or Picts, and were soon obliged to retreat to the south of the Cheviot Hills; where the great wall, with its many towers and deep ditches, which they had built from the Solway Firth to the River Tyne, became their chief defence against the harassing inroads of the Highland warriors. But this wall also was surmounted by the Picts, whose courage and daring increased in proportion as the power of the Romans, both at home and abroad, was rapidly waning. At last the Picts destroyed the wall, and after the fall of the Roman dominion, made incursions into England, where neither the descendants of the Romans, nor the Britons, found any means to repel them. It was not till the Anglo-Saxon conquest of England that the Picts were again compelled to fly towards the north over the Cheviot Hills, where they found sufficient employment in defending their own homes.