Rome and Persia had a long history with each other, which varied from neutral to negative depending on which period is being discussed. This culminated in a final conflict between the Byzantine Empire and the Sassanid Empire in the early 600s; both empires were weakened afterward, and the emergence of islam afterward completely conquers the Sassanid Empire for good.
My question is; is there any record of the Byzantines having any awareness of the Persians after that final war? To the best of my knowledge, anything mentioned afterward is almost exclusively through the periphery of islam, wherein the persians, if they ever interacted with the romans, seemingly identified themselves as islamic rather than persian. The khwarazmian empire, a decidedly more persian-esque empire, doesn't even have any mention of byzantine relations as far as I could see. The measurable roman-persian relations just seem to cease following the war, with the last possible reference being the Battle of Firaz.
I get that this is probably poorly worded, but I haven't a clue where to look, given how the conversation could get awkward.
One example of this came in the reign of Theophilos, where a number of Persian soldiers that had joined the eventually failed Khurramite revolt of Babak Khoramdin against the Abbasids fled west and joined the Byzantine army to continue the struggle. These troops participated in the Abbasid campaigns of Theophilos, which had mixed success, such as in the setback at Anzen or Dazimon, which was lost in large part due to Theophilos' sudden troop movements causing confusion and morale loss in the byzantine army. Following this failure, one such Persian called Nasr, who had been converted to Christianity and adopted the name Theophobos was actually declared Basileus by the Khurramite Persian troops in the Persian army after a rumor spread that Theophilos had died in the battle.
Here is an article about these events: https://bmcr.brynmawr.edu/2015/2015.03.32/