It was formed in the year 296, during the reign of Emperor Diocletian. Previously, it was a part of the province of Pannonia Superior, which, along with Pannonia Inferior, was gradually divided into four administrative units: Pannonia Prima, Pannonia Secunda, Valeria, and Savia.
In 296, during Diocletian's reign, the entity came into being. Previously, it was a part of the Pannonia Superior province, which, along with Pannonia Inferior, was eventually divided into four administrative units: Pannonia Prima, Pannonia Secunda, Valeria, and Savia.