Here’s an excellent long interview with Adrian Goldsworthy by Garrett Ryan on the Roman and Persian (Parthian and Sassanian) rivalry that spanned seven centuries.
Goldsworthy makes the point that there is more of a continuity between the Parthians and Sassanians than modern historians usually state.
Despite the numerous and often bloody conflicts, Goldsworthy explores the often beneficial trade between the cultures and the possibility that mutual respect (as well as internal struggles and constraints of geography) prevented their trying to totally vanquish the other. Usually, the conflict between the Romans and Persia was a struggle for influence rather than direct control. Armenia was often the source of this struggle.
Recommend highly.