Apart from the more or less conventional rendering of the human figure—and this is what we usually think of in connection with Byzantine painting—we find two tendencies in the minor arts of the time; one classical, carrying on the old Greco-Roman tradition, the other Oriental in motive and feeling. For more than three hundred years the frontiers of the Roman and Sassanian empires were continually fluctuating, and in this border region, which included Armenia, Georgia, Western Persia, and the upper waters of the Tigris and the Euphrates, there were at this time many flourishing centres of industry. It was probably in some of these lands, rather than in Constantinople itself, that we may look for the home of the school of carving in rock crystal and in glass that we associate vaguely with the Lower Empire.[72] Nor did the Arab conquests of the seventh and eighth centuries make at once any great changes in the arts of these districts. It was through these lands probably that so many Oriental motives filtered through to the west, not only to Constantinople, but to the north and west coasts of the Black Sea also, and thence through Poland and Hungary to Germany. Nowhere is this Oriental influence better seen than in the vases of rock crystal and other hard stones preserved in the treasuries of our Western churches, nor can we separate these vases from the even rarer objects carved in glass. The carving on the so-called Hedwig glasses is, as we shall see, executed in an allied if somewhat degenerate style; some of these glasses can be traced back to the borderlands of Poland. Of the glass in use among the Persians and the other subjects of the Sassanian empire (which lasted from the end of the third to the beginning of the seventh century) we know practically nothing. Doubtless many examples of Sassanian glass have been turned up during the gigantic explorations around Nineveh, Babylon, and Susa, but till quite lately little attention has been paid to objects of so comparatively late a date. In the Louvre are some fragments of glass lately brought from Susa. One piece calls for mention here. This is a large fragment of thick clear glass which has formed the half of a shallow circular dish, about fourteen inches in diameter. There are some eight or nine shallow circular depressions cut out from the sides, with a stud rising in counter-relief from the centre of each. We are at once reminded of certain ‘balance-pan’ hanging lamps in the treasury at Venice—in fact, this fragment from Susa must have formed part of a vessel almost identical with these.