The whole continent of Europe has now been laid out upon this system of strict delimitation. Yet it may be maintained that among the kingdoms of the ancient world no such exact and recognised distribution of territory existed; and, further, that up to a very recent period none of the great empires in Asia had any boundaries that could be traced on a map. Their landmarks were incessantly shifting forward or backward as their military strength rose or fell; and where their territories marched with some rough mountainous tract inhabited by warlike tribes, they were perpetually plagued by petty warfare on a zone of debateable land. On both sides some temporary intrusion upon or occupation of country held by a neighbour, which would now be the signal for mobilising an army, was treated as a trespass of small importance, to be resented and rectified at leisure. It is true that in earlier times the Romans marked off distinct frontiers, and guarded them by military posts; but their policy was to acknowledge no frontier power with equal rights, and their actual political jurisdiction usually extended far beyond their lines of defence, which were advanced or withdrawn as political or military considerations might require. In fact, the Roman empire, like the British empire in Asia, was a great organised State, surrounded, for the most part, by small and weak principalities, or by warlike tribal communities, and it grew by a natural process of inevitable expansion. The emperors were often reluctant to enlarge their possessions; but the raids and incursions of intractable barbarians, or the revolt of some protected chiefship, frequently left them no option but to conquer and annex. They soon found themselves compelled to overstep the limits of empire prescribed by the policy of Augustus, and to lay down an advanced frontier in the lands beyond the Rhine and the Danube.
In Europe, where, as we have said, all national frontiers are now fixed and registered, the position of a civilised government entangled in chronic border warfare has long been unknown; the tradition of such a state of things is preserved in popular recollection mainly by local records and old ballads. Yet for Englishmen the subject possesses peculiar interest, since it is connected with their earlier history; and moreover our dominion in India invests it with special importance, for it is there a matter of immediate experience and active concern. We may recollect, in the first place, that Britain was an outlying province of the Roman empire, for at this moment we are excavating the ruins of the wall built by the Romans to protect their northern frontier from the incursions of the warlike tribes beyond it, by the first administration that established, for a time, peace and civilisation in England. Then, in the middle ages, and long afterwards, the border between the kingdoms of England and Scotland which ran northward of the old Roman line, was for centuries the scene of plundering raids, punitive expeditions, and internecine feuds that often laid waste the countryside with fire and sword. We may observe, in this instance, how shifting and indeterminate was the exact frontier line between the two kingdoms, and how the local fighting, the inroads from one side or the other, did not necessarily involve a rupture of their formal relations. The wardens on each side executed rough justice upon marauding clans; they wasted and slaughtered in reprisal for raids; the great nobles engaged in a kind of private warfare; but all this might go on without embroiling the two governments in a national war. On the western English border the Welsh hillmen kept the neighbouring counties in continual alarm; and their chiefs played an important part in the civil wars and rebellions of England. They were at last quieted by Edward I., who succeeded in subduing Wales though he failed in Scotland. Lastly, though the union of the two kingdoms brought peace to the Anglo-Scottish border, the Highland line along the Forth river still kept up, though in a much less serious degree, the troubles of a regular government in contact with restless tribes. Nor was it until the middle of the eighteenth century that these relics of an archaic condition of society, which had long ago disappeared in other parts of western Europe, were finally effaced in Great Britain. Long afterwards, in the nineteenth century, when the conquest of the Punjab carried the north-western frontier of British India up to the slopes of the Afghan mountains, the scene of perpetual strife between a strong settled administration and turbulent borderers which had passed away on the Tweed or the Forth, and on the Welsh Marches, reappeared in the districts beyond the Indus.