a role filled for the Persians by Nisibis (which until its secession in 363 had served the same purpose for the Romans), and in 505 Anastasius therefore ordered the building of a great fortified city at Dara. The dilapidated fortifications were also upgraded at Edessa, Batnae and Amida. Although no further large-scale conflict took place during Anastasius's reign, tensions continued, especially while work continued at Dara. This construction project was to become a key component of the Roman defenses, and also a lasting source of controversy with the Persians, who complained that its construction violated the treaty agreed in 422, by which both empires had agreed not to establish new fortifications in the frontier zone. Anastasius, however, pursued the project, deflecting Kavad's complaints with money. The Persians were in any case unable to stop the work, and the walls were completed by 507/508. References Sources Primary Books I–II. Secondary 500s in the Byzantine Empire 6th century in Iran 500s conflicts Roman–Sasanian Wars 6th century in Asia 500s 502 506