Which language served as the main administrative language of the Achaemenid Empire?

Imperial Aramaic served as the main administrative language of the Achaemenid Empire. Persian officials used it for correspondence and record-keeping across territories extending from Egypt and Anatolia to Central Asia.

Aramaic was already widely used in the Near East before the Achaemenid conquest, and its alphabet was relatively practical for communication among different peoples. The empire therefore used it as a shared bureaucratic language even though Old Persian was the language of royal inscriptions and Persian identity.

This distinction causes a common mix-up: Old Persian, Elamite, and Babylonian appear together in famous royal inscriptions such as those at Persepolis and Behistun, but Aramaic was especially important in day-to-day imperial administration. Surviving documents include letters, tax records, and military communications.