Parker (2006:121) described Stratum III—the final phase of significant occupation— as beginning “with the demobilization of the legion ca. 530,” based on a passage in Procopius (Anecdota 24.12–14). Parker noted that “the latest closely dateable Byzantine coins from el-Lejjun are issues of Justinian I dated 534–565, exactly what one would expect if Procopius’ assertion were true.” He added that “some structures like the principia were completely abandoned,” while “others, like the church, were extensively robbed.” Large quantities of trash were dumped in barrack alleyways and even in major thoroughfares such as the via praetoria.” “In Area N,” Parker continued, “the rooms rebuilt after 502 afterward witnessed little actual occupation,” adding that “it is especially telling that a human corpse was interred in one room (N.2) that opened directly onto the via principalis—a clear sign of the absence of military discipline.” Parker (2006:121) continued: “Some inhabitants, perhaps discharged soldiers and their families or civilians from the surrounding countryside, continued to live within the fortress.” He observed that “the discovery of a human infant within the northwest angle tower in the debris of the earthquake of July 9, 551, implies that families were now living in the fortifications,” concluding that “the earthquake of 551 was a major catastrophe.” While the archaeoseismic evidence for this third earthquake is strong, the causative event was more likely the nearby late sixth-century Inscription at Aeropolis Quake rather than the distant 551 CE Beirut Quake.

The numismatic finds and evidence for demobilization described above provide a terminus post quem of approximately 530 CE for seismic destruction and the final abandonment of the fortress at el-Lejjun. A terminus ante quem is less precisely defined because, after the third earthquake, a long Post Stratum Gap ensued that lasted until 1900 CE. Parker (2006:121) reports that “there is some evidence of camping and limited reoccupation of the domestic complex near the north gate in the Umayyad period (661–750 CE).” He further notes that “sherds and coins of Ayyubid/Mamluk (1174–1516) and Ottoman periods attest occasional later use of the fortress.” Because Groot et al. (2006:183) report the discovery of a nearly complete Umayyad lamp in Square 4 of Area B (Barracks) within the Post Stratum Gap, the Umayyad period (661–750 CE) provides the most probable terminus ante quem for the “third earthquake.” The date of this earthquake is therefore constrained to approximately 530–750 CE. de Vries et al. (2006:196) likewise identified Umayyad sherds in the Post Stratum Gap in Rooms C.3, C.4, C.6, and C.7 of the northwest angle tower, together with an Umayyad coin dated 700–750 CE in locus C.4.018.