including the states of Caucasian Iberia, Armenia, Atropatene, Gordyene, Adiabene, Edessa, Hatra, Mesene, Elymais, and Persis. The state rulers governed their own territories and minted their own coinage distinct from the royal coinage produced at the imperial mints. This was not unlike the earlier Achaemenid Empire, which also had some city-states, and even distant satrapies who were semi-independent but "recognised the supremacy of the king, paid tribute and provided military support", according to Brosius. However, the satraps of Parthian times governed smaller territories, and perhaps had less prestige and influence than their Achaemenid predecessors. During the Seleucid period, the trend of local ruling dynasties with semi-autonomous rule, and sometimes outright rebellious rule, became commonplace, a fact reflected in the later Parthian style of governance. Nobility The King of Kings headed the Parthian government. He maintained polygamous relations, and was usually succeeded by his first-born son. Like the Ptolemies of Egypt, there is also record of Arsacid kings marrying their nieces and perhaps even half-sisters; Queen Musa is said by Josephus to have married her own son, though this would be an extreme and isolated case. Brosius provides an extract from a letter written in Greek by King Artabanus II in 21 AD, which addresses the governor (titled "archon") and citizens of the city of Susa. Specific government offices of Preferred Friend, Bodyguard and Treasurer are mentioned and the document also proves that "while there were local jurisdictions and proceedings to appointment to high office, the king could intervene on behalf of an individual, review a case and amend the local ruling if he considered it appropriate." The hereditary titles of the hierarchic nobility recorded during the reign of the first Sasanian monarch Ardashir I most likely reflect the titles already in use during the Parthian era. There were three distinct tiers of nobility, the highest being the regional kings directly below the King of Kings, the second being those related to the King of Kings only through marriage, and the lowest order being heads of local clans and small territories. By the 1st century AD, the Parthian nobility had assumed great power and influence in the succession and deposition of Arsacid kings. Some of the nobility functioned as court advisers to the king, as well as holy priests. Strabo, in his Geographica, preserved a claim by the Greek philosopher and historian Poseidonius that the Council of Parthia consisted of noble