It would, however, be easy to show that in assigning a more definite value to the terms in question--a proceeding in which we have the countenance of nearly every modern historian--we do not detach them from their original acceptation; at most we give them more constancy and precision than the colloquial language of the Greeks and Romans demanded.[12] The expressions _Khasdim_ and _Chaldaei_ were used in the Bible and by classic authors mainly to denote the inhabitants of Babylon and its neighbourhood; and we find Strabo attaching with precision the name _Aturia_, which is nothing but a variant upon Assyria, to that district watered and bounded by the Tigris in which Nineveh was situated.[13] Our only aim is to adopt, once for all, such terms as may be easily understood by our readers, and may render all confusion impossible between the two kingdoms, between the people of the north and those of the south. In order to define Assyria exactly we should have to determine its frontiers, and that we can only do approximately. As the nation grew its territory extended in certain directions. To the east, however, where the formidable rampart of the Zagros forbade all progress, no such extension took place. Those lofty and precipitous chains which we now call the mountains of Kurdistan, were only to be crossed in two or three places, and by passes which during their few months of freedom from snow and floods gave access to the high-lying plains of Media. These narrow defiles might well be traversed by an army in a summer campaign, but neither dwellings nor cultivated lands could invade such a district with success; at most they could take possession of the few spots of fertile soil which lay at the mouth of the lateral valleys; such, for example, was the plain of Arbeles which was watered by the great Zab before its junction with the Tigris. Towards the south there was no natural barrier, but in that direction all development was hindered by the density of the Chaldee population which was thickly spread over the country above Babylon and about the numerous towns and villages which looked towards that city as their capital. To the north, on the other hand, the wide terraces which mounted like steps from the plains of Mesopotamia to the mountains of Armenia offered an ample field for expansion. To the west there was still more room. Little by little rural and urban life overflowed the valley of the Tigris into that of the Chaboras or Khabour, the principal affluent of the Euphrates, until at last it reached the banks of the great western river itself. In all Northern Mesopotamia, between the hills of the Sinjar and the last slopes of Mount Masius, the Assyrians encountered only nomad tribes whom they could drive when they chose into the Syrian desert. Over all that region the remains of artificial mounds have been found which must at one time have been the sites of palaces and cities. In some cases the