These monuments of an epoch between remote antiquity and the Graeco-Roman period were built of brick, like the palaces of Nineveh.[207] The exigencies of the climate remained the same, the habits and requirements of the various royal families that succeeded each other in the country were not sensibly modified, while the Sargonids, the Arsacids and the Sassanids all ruled over one and the same population. [Illustration: FIG. 52.--The Palace at Firouz-Abad; from Flandin and Coste.] [Illustration: FIG. 53.--The palace at Sarbistan; from Flandin and Coste.] The corporations of architects and workmen must have preserved the traditions of their craft from century to century, traditions which had their first rise in the natural capabilities of their materials and in the data of the problem they had to solve. The historian cannot, then, be accused of going beyond the limit of fair induction in arguing from these modern buildings to their remote predecessors. After the conquest of Alexander, the ornamental details, and, still more, the style of the sculptures, must have been affected to a certain extent, first by Greek art and afterwards by that of Rome; but the plans, the internal structure, and the general arrangement of the buildings must have remained the same. [Illustration: FIG. 54.--Section through the palace at Sarbistan; from Flandin and Coste.] There is nothing hazardous or misleading in these arguments from analogy; from the palace of Chosroes to that of Sargon is a legitimate step. Some day, perhaps, we may attempt to pursue the same path in the opposite direction; we may endeavour to show that the survival of these examples and traditions may very well have helped to direct architecture into a new path in the last years of the Roman Empire. We shall then have to speak of a school in Asia Minor whose works have not yet been studied with the attention they deserve. The buildings in question are distinguished chiefly by the important part played in their construction by the vault and the dome resting upon pendentives; certain constructive processes, too, are to be found in them which had never, so far as we can tell, been known or practised in the East. We can hardly believe that the chiefs of the school invented from the foundation a system of construction whose principles were so different from those of the Greeks, or even of the later Romans. They may, indeed, have perfected the system by grafting the column upon it, but it is at least probable that they took it in the first place from those who had practised it from time immemorial, from men who taught them the traditional methods of shortening and facilitating the labour of execution. The boundaries of Asia Minor "march" with those of Mesopotamia, and in the latter every important town had buildings of brick covered with domes. The Romans frequented the Euphrates valley, to which they were taken both by war and commerce; their victories sometimes carried them even as far as