Bingley! You've gone Carpal too! CONGRATULATIONS!!

What contact was there between Latin speakers and Persians at the time when barbicans were being built?

I don't know about the missing language links, Bing, but I can tell you something about the historical connections. At the turn of the first millenium AD, in the last centuries BC, the Western Eurasian Steppe was inhabited by the Iranian Scythians; they gave way to the, Iranian again, Sarmatians - these people used a lot of ornate weaponry and gilt in their swords and jewelry. Around 2AD, I think, the Goths came into the Western Steppe from the Baltic. There followed a significant intermixion of the cultures of the Goths and the Sarmatians and what is currently referred to as the Gothic style is actually ascribed to the Sarmatians. The Mongols (?4-5AD) came in from the Eastern Steppe and displaced the nomadic Goth-Sarmatians into the very heart of Western Europe. With them they took the Iranian language, religion, and culture into Western Europe and these influences are seen to this very day. There was one Sarmatian tribe, I forget the name, that to this day lends its name to a city/town in France.

A castle from the region with a good example of barbican fortressing is in Dagestan in Azerbaijan. Again, the name evades my memory. This architecture is borrowed from the region of the Caucasus and the modern day Iranian plateau.

Khan is pronounced Khan-eh in Farsi and a married lady is called Khanum. Say jheem's wife (before I get another disclaimer, Bingley! ) will be respectfully addressed as, Khanum-eh-jheem!