The Roman- Sassanian conflicts in late Roman period: The eastern borders of Rome

During the III century A.D, the first Roman-Sassanid controversies took place during the rule of Ardashir I and Alexander Severus. This controversy began after Ardashir I wanted the lands back from Romans, over which his ancestors reigned. As a result of these conflicts, the sources used in the text, except for Herodianus, says that Alexander Severus was successful. But Persian attacks couldn?t be stopped and a confrontation again took place between the new Emperor Gordian III and Shapur I . Gordian who was successful in the beginning either died in the war (Misiche) after the death of his praetor praefectus, Timesitheus or was killed because of the betrayal of Philippus Araps who became Emperor after him. After the death of Gordian, Philippus Araps made an agreement to give Mesopotamia and Armenia to the Persians in 244 A.D. however, Shapur I continued his expeditions against Rome and the aggressive policy; capturing many cities belonging to Rome and seized Tarsus, a Cilicia city, moving to the Mediterranean coast. In 260 A.D. he took the Emperor Valerian, his commanders and soldiers as captives in the confrontation with the Emperor. Rome, with the Emperor inconsistent because of the crisis, found the solution in giving imperial authorization to its ally Odaenathus the King of Palmyra. Odaenathus had great successes against Shapur I and drove Shapur from Mesopotamia and Syria. However, after these, Odaenathus attempted to keep going to Rome with the ambition arising from these success but failed to realise his imperial ambitions. After Odaenathus died, his wife Zenobia became a new enemy of Rome and invaded Roman Egypt and Arabia. After that, the Emperor Aurelian moved forward to Palmyra, caught Zenobia and made the country a desert. Meanwhile, Shapur I died and Bahram ascended the crown and, according to the Historia Augusta, he proposed peace to the Roman Emperor Probus. When Emperor Carus began to reign with his sons, he went on an expedition against the Sassanids, beat them but died in his military camp in Ctesiphon struck by a bolt of lightning. When the Sassanid Emperor Narseh ascended the throne, he also continued the policy to counter attack Rome like his ancestors and as a result of this, he battled against Galerius in 297 A.D. At the end of the war, he escaped; but his harem and his valuable belongings were captured by Galerius. In 298 A.D. peace was made between Narseh and Diocletian, Narseh was obliged to accept all the conditions set by Rome. When Shapur II ascended the throne, the golden time for the Sassanids began. Shapur II generally won his battles against Constantius II; blockaded Nisibis three times and captured Singara. After the death of Constantius, his heir Julian attempted an expedition to Persian and moved forward to Ctesiphon the capital city of Sassanids capturing many cities in Mesopotamia. However, his death while fighting in enemy land, left Rome without an Emperor. The chosen Emperor Jovian, made an extremely shameful but necessary agreement with Shapur II in 363 A.D. According to is the conquered lands were given back to the Persians and this peace was valid for nearly thirty years. In 379 A.D., after Shapur II died, Sassanids left their magnificence behind. In 383/384 A.D. a peace was made between Theodosius I and Shapur III again; Armenia was shared between two empire and the strategic regions on the upper Tigris and Euphrates was left to Theodosius, but Nisibis and Singara were left to Persians