The divisions of the empire which he founded can be sketched by the aid of an excerpt from the itinerary of Isidore of Charax (at the beginning of the Christian era) and from Pliny. The empire was divided into the upper and lower kingdoms, separated by the Caspian Gates. The lower kingdoms were seven: (1) Mesopotamia and Babylonia, (2) Apolloniatis, (3) Chalonitis, (4) Carina, (5) Cambadene, (6) Upper Media, (7) Lower or Rhagian Media. The upper kingdoms were eleven: (8) Choarene, (9) Comisene, (10) Hyrcania, (11) Astauene, (12) Parthyene, (13) Apauarcticene, (14) Margiana, a part of Bactria, (15) Aria, (16) the country of the Anauans, (17) Zarangiana, and (18) Arachosia, now called “White India.” The eighteen Parthian kingdoms thus correspond to six old satrapies. The Parthians gave much less attention to the west than did their predecessors, and they still left Mesopotamia as the only great satrapy. We note also that they cared little for reaching the sea, which they can have touched only for a little way at the mouth of the Euphrates; and even here they allowed the petty Characene quite to outstrip them in competing for the great sea trade. As compared with the older Macedonian Empire, the Parthian realm lacked the east Iranian satrapies, Bactria with Sogdiana, and the Paropanisadæ, and also the three Indian ones, which, with Parætacene, or as it was afterwards called Sacastane, remained under the Bactrian Greeks and their successors. In the north they lacked Lesser Media, which had long been an independent state, and in the south they lacked Susiana, which now belonged to Elymais, and the satrapies of Persis and Carmania, which the Persians held along with the western part of Gedrosia. In the extreme west they lacked Arebelitis proper, which formed a small kingdom under the name of Adiabene, first mentioned in 69 B.C. The kingdom of Mannus of Orrha in northern Mesopotamia, which according to Isidore reached a good way south of Edessa, seems also to have been independent, and, like Adiabene, probably existed before the Parthian time. From these small kingdoms the Parthians asked only an acknowledgment of vassalship. When Parthia was vigorous the vassalship was real, but when Parthia was torn by factions it became a mere name. The relation was always loose, and the political power of Parthia was therefore never comparable to the later power of the Sassanians. Arsaces Tiridates and his successors called themselves “great king.” Mithridates, as overlord of the minor kingships, first bore the title “great king of kings.” The title seems to have been conferred, not assumed in mere boastfulness.