forget the fall of the seleukia, the arab invasion and islamification of persia, now that was a true catastrophe!
I totally agree !

This also goes to why the England/France debate misses the point, namely that they're still England/France because the people who live there are English and French. The question isn't maintenance of nationhood, but maintenance of empire.

The same with the Seleukids.. greeks survived, but their empires fall appart.