[phkahler]

> Society and its rulers are not the same thing.

I wanted to make that point when I read this line:

>> But the Avars ruled Central Europe for over two centuries, and it is not a given that their civilization had no worth and did not represent a future we would have flourished in.

A civilizations worth is always measured by those who might seek to control it. You could have a bunch of people getting on just fine, living out perfectly normal lives. But if there isn't any way for them to produce excess - be that labor output or extraction of natural resources - then they are not seen as valuable and will not be written about.