 It can be no earlier than about 400 BC, but is probably later, possibly even as late as 336–331 BC (the reign of Darius III, the last Persian king); it probably circulated as an independent document before being combined with Ezra.There are seven Persian documents embedded in Ezra–Nehemiah, six in Ezra and one in Nehemiah.All but one are in Aramaic language, the administrative language of the Persian empire.