Such were the people in Alba whom we can dimly descry around Agricola's fortified frontier between the firths of Forth and Clyde, about 81-82 A.D. When Agricola pushed north of the Forth and Tay he still met men who had considerable knowledge of the art of war. In his battle at Mons Graupius (perhaps at the junction of Isla and Tay), his cavalry had the better of the native chariotry in the plain; and the native infantry, descending from their position on the heights, were attacked by his horsemen in their attempt to assail his rear. But they were swift of foot, the woods sheltered and the hills defended them. He made no more effectual pursuit than Cumberland did at Culloden. Agricola was recalled by Domitian after seven years' warfare, and his garrisons did not long hold their forts on his lines or frontier, which stretched across the country from Forth to Clyde; roughly speaking, from Graham's Dyke, east of Borrowstounnis on the Firth of Forth, to Old Kilpatrick on Clyde. The region is now full of coal-mines, foundries, and villages; but excavations at Bar Hill, Castlecary, and Roughcastle disclose traces of Agricola's works, with their earthen ramparts. The Roman station at Camelon, north-west of Falkirk, was connected with the southern passes of the Highland hills by a road with a chain of forts. The remains of Roman pottery at Camelon are of the first century. Two generations after Agricola, about 140-145, the Roman Governor, Lollius Urbicus, refortified the line of Forth to Clyde with a wall of sods and a ditch, and forts much larger than those constructed by Agricola. His line, "the Antonine Vallum," had its works on commanding ridges; and fire-signals, in case of attack by the natives, flashed the news "from one sea to the other sea," while the troops of occupation could be provisioned from the Roman fleet. Judging by the coins found by the excavators, the line was abandoned about 190, and the forts were wrecked and dismantled, perhaps by the retreating Romans. After the retreat from the Antonine Vallum, about 190, we hear of the vigorous "unrest" of the Meatae and Caledonians; the latter people are said, on very poor authority, to have been little better than savages. Against them Severus (208) made an expedition indefinitely far to the north, but the enemy shunned a general engagement, cut off small detachments, and caused the Romans terrible losses in this march to a non- existent Moscow. Not till 306 do we hear of the Picts, about whom there is infinite learning but little knowledge. They must have spoken Gaelic by Severus's time (208), whatever their original language; and were long recognised in Galloway, where the hill and river names are Gaelic. The later years of the Romans, who abandoned Britain in 410, were perturbed by attacks of the Scoti (Scots) from Ireland, and it is to a settlement in Argyll of "Dalriadic" Scots from Ireland about 500 A.D. that our country owes the name of Scotland.