At the centre of ancient Persian administration was the king, controlling a network of satraps (governors). As well as governing, satraps were responsible for securing tribute and delivering it to the royal palace. The Greek writer Herodotus reported that at one time Cilicia (in south-east Turkey) paid 500 talents of silver (about 14 metric tons) and provided 360 white horses, and Babylon and Assyria paid 1000 talents of silver (about 28 metric tons) and gave 500 boys to be eunuchs.

The system seems to have been a flexible one. The Athenian nobleman Xenophon noted that some areas of the empire were exempt from tribute at certain times because of services provided for the king. Politically the satrapies worked because they were able to accommodate existing habits in different parts of the empire. This tolerance also extended to regional variations in religious beliefs.

The Persians were also realistic in their approach to the use of different languages within the empire. Although Old Persian was the official language of the rulers, Elamite and Babylonian were also spoken. The Egyptian language was used in Egypt, and Greek was used by the western satraps when they communicated with the Greeks.

In the 1930s some 30,000 clay tablets were found at Persepolis. They cover the short period between 509 and 494 BC but give a fascinating insight into what must have been high levels of bureaucracy. Tablets and documents were often sealed with cylinder seals and stamp seals, some of which survive. Cylinder seals were rolled over wet clay to produce impressions.