Ostraca (ink inscriptions on clay) from the Iron Age fortress of Arad, located in arid southern Judah. These documents are dated to the latest phase of the First Temple Period in Judah, ca. 600 BCE. The texts represent correspondence of local military personnel. The research engaged new document analysis algorithms aimed at identifying different writers. It detected at least six contemporaneous authors within a corpus of 16 inscriptions. This indicates a high literacy level within the Judahite administration and provides a possible stage-setting for compilation of biblical texts.