G. 7.—­The practical importance of the above-mentioned natural divisions of the island is testified to by the abiding character of the corresponding political divisions.  The resemblance which at once strikes the eye between the map of Roman and Saxon Britain is no mere coincidence.  Physical considerations brought about the boundaries between the Roman “provinces” and the Anglo-Saxon principalities alike.  Thus a glance will show that Britannia Prima, Britannia Secunda, Maxima Caesariensis, and Flavia Caesariensis correspond to the later Wessex, Wales, Northumbria, and Mercia (with its dependency East Anglia).[49] And even the sub-divisions remained approximately the same.  In Anglo-Saxon times, for example, the Midlands were still divided into the same four tribal territories; the North Mercians holding that of the British Cornavii, the South Mercians that of the Dobuni, the Middle Angles that of the Coritani, and the South Angles that of the Cateuchlani.  So also the Icenian kingdom, with its old boundaries, became that of the East Angles, and the Trinobantian that of the East Saxons.

G. 8.—­What the entire population of Britain may have numbered at the Roman Conquest is, again, purely a matter of guess-work.  But it may well have been not very different in amount from what it was at the Norman Conquest, when the entries in Domesday roughly show that the whole of England (south of the Humber) was inhabited about as thickly as the Lake District at the present day, and contained some two million souls.  The primary hills, and the secondary plateaux, where now we find the richest corn lands of the whole country, were in pre-Roman times covered with virgin forest.  But in the river valleys above the level of the floods were to be found stretches of good open plough land, and the chalk downs supplied excellent grazing.  Where both were combined, as in the valleys of the Avon and Wily near Salisbury, and that of the Frome near Dorchester, we have the ideal site for a Celtic settlement.  In such places we accordingly find the most conspicuous traces of the prehistoric Briton; the round barrows which mark the burial-places of his chiefs, and the vast earthworks with which he crowned the most defensible dun, or height, in his territory.

G. 9.—­These fortified British duns are to be seen all over England.  Sometimes they have become Roman or mediaeval towns, as at Old Sarum; sometimes they are still centres of population, as at London, Lincoln, and Exeter; and sometimes, as at Bath and Dorchester, they remain still as left by their original constructors.  For they were designed to be usually untenanted; not places to dwell in, but camps of refuge, whither the neighbouring farmers and their cattle might flee when in danger from a hostile raid.  The lack of water in many of them shows that they could never have been permanently occupied either in war or peace.[50] Perhaps the best remaining example is Maiden[51] Castle, which dominates