During the time Justinian’s generals were changing the state of Europe and destroying some of the nations which had dismembered the Western Empire, circumstances beyond the control of that international system of policy, of which the sovereigns of Constantinople and Persia were the arbiters, produced a general movement in the population of central Asia. The whole human race was thrown into a state of convulsive agitation, from the frontiers of China to the shores of the Atlantic. This agitation destroyed many of the existing governments, and exterminated several powerful nations; while, at the same time, it laid the foundation of the power of new states and nations, some of which have maintained their existence to the present times. The Eastern Empire bore no inconsiderable part in raising this mighty storm in the West and in quelling its violence in the East, in exterminating the Goths and Vandals, and in arresting the progress of the Avars and Turks. Yet the number and composition of the Roman armies have often been treated by historians as weak and contemptible. It is impossible, in this sketch, to attempt any examination of the whole military establishment of the Roman Empire during Justinian’s reign; but in noticing the influence exercised by the military system on the Greek population, it is necessary to make a few general observations. The army consisted of two distinct classes--the regular troops, and the mercenaries. The regular troops were composed both of native subjects of the Roman Empire, raised by conscription, and of barbarians, who had been allowed to occupy lands within the emperor’s dominions and to retain their own usages on the condition of furnishing a fixed number of recruits for the army. The Roman government still clung to the great law of the empire, that the portion of its subjects which paid the land tax could not be allowed to escape that burden by entering the army. The proprietors of the land were responsible for the tribute; the cultivators of the soil, both slaves and serfs, secured the amount of the public revenues; neither could be permitted to forego their fiscal obligations for their military duties.