Anastasian War The Anastasian War was fought from 502 to 506 between the Eastern Roman Empire and the Sassanid Empire . It was the first major conflict between the two powers since 440 , and would be the prelude to a long series of destructive conflicts between the two empires over the next century . Prelude . Several factors underlay the termination of the longest period of peace the Eastern Roman and the Sassanid Empire ever enjoyed . The Persian king Kavadh I needed money to pay his debts to the Hephthalites who had helped him regain his throne in 498 / 499 . The situation was exacerbated by recent changes in the flow of the Tigris in lower Mesopotamia , sparking famines and flood . When the Roman emperor Anastasius I refused to provide any help , Kavadh tried to gain the money by force . War . In 502 , Kavadh quickly captured the unprepared city of Theodosiopolis , perhaps with local support ; the city was in any case undefended by troops and weakly fortified . Kavadh then besieged the fortress - city of Amida through the autumn and winter ( 502 - 503 ) . The siege of the city proved to be a far more difficult enterprise than Kavadh expected ; the defenders , although unsupported by troops , repelled the Persian assaults for three months before they were finally beaten . The year 503 saw much warfare without decisive results : the Romans attempted an ultimately unsuccessful siege of the Persian - held Amida while Kavadh invaded Osroene , and laid siege to Edessa with the same results . Finally in 504 , the Romans gained the upper hand with the renewed investment of Amida leading to the hand - over of the city . That year , an armistice was agreed as a result of an invasion of Armenia by the Hun s from the Caucasus . Negotiations between the two powers took place , but such was the distrust that in 506 the Romans , suspecting treachery , seized the Persian officials ; once released , the Persians preferred to stay in Nisibis . In November 506 , a treaty was finally agreed , but little is known of what the terms of the treaty were . Procopius states that peace was agreed for seven years , and it is likely that some payments were made to the Persians . Aftermath . The Roman generals blamed many of their difficulties in this war on their lack of a major base in the immediate vicinity of the frontier , 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 Kavadh ' s complaints with money . The Persians were in any case unable to stop the work , and the walls were completed by 507 / 508 .