At least two autochthonous languages are amply attested: Old Persian and Elamite. The former is an Indo-European language, part of the Indo-Iranian branch; the latter is probably unrelated to any other. The speakers of Old Persian, the Achaemenid rulers and the ethnic group usually called Persian (after the region of Parsua, modern Fars), originally came from the area to the west of Lake Urmia. They spoke an Indo-European language close to Avestan, the language of the early Zoroastrian texts preserved in medieval copies, and Median was the third and most poorly attested ancient Iranian language. After the two decades of conquests of Cyrus II the Persians settled in the Iranian plateau.
The Proto-Elamite texts (from the mid-fourth millennium to 2200) remain essentially undeciphered. Although they resemble the archaic Mesopotamian texts from Uruk, both scripts are independent. The Elamite language, written with the cuneiform borrowed from Mesopotamia, can be divided into three dialects, divided by periods of gaps with no attestations:
• Old Elamite is attested during the Sargonic period. In the Old Babylonian period, there are a few Elamite incantations from Mesopotamia.
• Middle Elamite appears during the thirteenth and twelfth centuries, mostly in inscriptions and administrative documents from Tall-i Malyan in the highland of Anshan.
• Late Elamite is the language of the texts written during the last century of independence of Elam (717-640 bce). Achaemenid Elamite is the language written under the Persian kings.
Elamite is an agglutinative language, but the number of suffixes is substantially smaller than those of Sumerian and Hurro-Urartian. Nouns exhibit classifier endings, based on the gender opposition between animate and inanimate. The verbal system has two finite forms, perfective and imperfective, and two voices, active and passive.
Old Persian nouns can be of three genders, masculine, feminine, and neuter. Nouns, adjectives, and pronouns can occur in three numbers, singular, plural, and dual, and six cases. The verbal system has three finite forms: present, imperfect, and a perfect made with the verb to be and the past participle. This system clearly contrasts with that of Hittite, which is simpler. Old Persian has two voices: active and middle. The middle voice is used both for reflexive and passive constructions.
Of the more than 30,000 Achaemenid tablets and fragments found dating from 509 to 458 BCE, two are in Babylonian, one in Greek, one in Phrygian, and the overwhelming majority in Elamite (Lewis 1994). Some of these tablets have Aramaic glosses inscribed on the clay, some tablets are bilingual with Babylonian and Aramaic, and some written exclusively in Aramaic.
In the history of cuneiform studies it is the trilingual inscription with Babylonian, Old Persian, and Elamite, of Darius in Bisitun (also sometimes called Behistun) that opened the door to the decipherment of cuneiform. The language diversity points to the ethnic complexity of the empire, which conflicted with the conservatism of the Elamite scribal tradition. The Old Persian script was not used until Darius. It is difficult to know whether this script was invented during Darius’ reign, but it was devised to write Median rather than Old Persian.
The Elamite version of the Bisitun inscription states that this is the first time an inscription was made in ‘‘Aryan.’’ This probably refers to the originally Median script. Scholars agree that the Elamite version was the first to be engraved, then the Babylonian, and finally the Old Persian. Most Persepolis scribes bore Elamite names, which may be an indicator of their ethnicity.