The administration lay in the hands of the under-kings or satraps; according to the Roman geographers of Vespasian’s time the state of the Parthians consisted of eighteen “kingdoms.” Some of these satrapies were appanages of a second son of the ruling house; in particular the two north-western provinces, the Atropatenian Media (Aderbijan) and Armenia, so far as it was in the power of the Parthians, appear to have been entrusted for administration to the prince standing next to the ruler for the time.[7] We may add that prominent among the satraps were the king of the province of Elymais or of Susa, to whom was conceded a specially powerful and exceptional position, and next to him the king of Persis, the ancestral land of the Achaemenids. The form of administration, if not exclusive, yet preponderant and conditioning the title, was in the Parthian empire--otherwise than in the case of the Caesars--that of vassal-kingdom, so that the satraps entered by hereditary right, but were subject to confirmation by the great-king.[8] To all appearance this continued downwards, so that smaller dynasts and family chiefs stood in the same relation to the under-kings as the latter occupied to the great-king.[9] Thus the office of great-king among the Parthians was limited to the utmost in favour of the high aristocracy by the accompanying subdivision of the hereditary administration of the land. With this it is quite in keeping, that the mass of the population consisted of persons half or wholly non-free,[10] and emancipation was not allowable. In the army which fought against Antonius there are said to have been only 400 free among 50,000. The chief among the vassals of Orodes, who as his general defeated Crassus, marched to the field with a harem of 200 wives and a baggage train of 1000 sumpter-camels; he himself furnished to the army 10,000 horsemen from his clients and slaves. The Parthians never had a standing army, but at all times the waging of war here was left to depend on the general levy of the vassal-princes and of the vassals subordinate to these, as well as of the great mass of the non-free over whom these bore sway. [Sidenote: The Greek towns of the Parthian empire.]