stylistic:style_transfer, stylistic:tone
Languages

During the reign of Cyrus II and Darius I, and as long as the seat of government was still at Susa in Elam, the language of the chancellery was Elamite. This is primarily attested in the Persepolis fortification and treasury tablets that reveal details of the day-to-day functioning of the empire. In the grand rock-face inscriptions of the kings, the Elamite texts are always accompanied by Akkadian (Babylonian dialect) and Old Persian inscriptions, and it appears that in these cases that the Elamite texts are translations of the Old Persian ones. It is then likely that although Elamite was used by the capital government in Susa, it was not a standardized language of government everywhere in the empire. The use of Elamite is not attested after 458 BC.

Following the conquest of Mesopotamia, the Aramaic language (as used in that territory) was adopted as a "vehicle for written communication between the different regions of the vast empire with its different peoples and languages. The use of a single official language, which modern scholarship has dubbed "Official Aramaic" or "Imperial Aramaic", can be assumed to have greatly contributed to the astonishing success of the Achaemenids in holding their far-flung empire together for as long as they did." In 1955, Richard Frye questioned the classification of Imperial Aramaic as an " official language ", noting that no surviving edict expressly and unambiguously accorded that status to any particular language. Frye reclassifies Imperial Aramaic as the lingua franca of the Achaemenid empire, suggesting that the use of Aramaic language in Achaemenid empire was more widespread than generally thought. Many centuries after the fall of the empire, Aramaic script and—as ideograms —Aramaic vocabulary would survive as the essential characteristics of the Pahlavi writing system.

Although Old Persian also appears on some seals and art objects, that language is attested primarily in the Achaemenid inscriptions of Western Iran, suggesting then that Old Persian was the common language of that region. However, by the reign of Artaxerxes II, the grammar and orthography of the inscriptions was so "far from perfect" that it has been suggested that the scribes who composed those texts had already largely forgotten the language, and had to rely on older inscriptions, which they to a great extent reproduced verbatim.

When the occasion demanded, Achaemenid administrative correspondence was conducted in Greek, making it a widely used bureaucratic language. Even though the Achaemenids had extensive contacts with the Greeks and vice versa, and had conquered many of the Greek-speaking areas both in Europe and Asia Minor during different periods of the empire, the native Old Iranian sources provide no indication of Greek linguistic influence. However, there is plenty of evidence (in addition to the accounts of Herodotus) that Greeks, apart from being deployed and employed in the core regions of the empire, also evidently lived and worked in the heartland of the Achaemenid Empire, namely Iran. For example, Greeks were part of the various ethnicities that constructed Darius' palace in Susa, apart from the Greek inscriptions found nearby there, and one short Persepolis tablet written in Greek.