Iranians in medieval Scotland
This post doesn't cite any Iranian language materials directly, but I dare say that Iranian speakers were involved in the transmission of this large hoard from western Central Asia more than a thousand miles distant and were present in the British Isles during the first millennium AD.
"Amazing’ Viking-age treasure travelled half the world to Scotland, analysis finds", by Dalya Alberge, The Guardian (Sun 1 Sep 2024)
Lidded vessel is star object in rich Galloway Hoard and came from silver mine in what is now Iran