Ian, most, perhaps all of your examples of medieval song date from the late medieval period, so later than 11th century. Do we know anything about secular music in the early medieval period, the European "dark ages". We know about Gregorian chant, and the Wikipedia article seems pretty good here.

Also, how much do we know about early music in other cultures, for instance China or India?

Your articles are fascinating reading, and I for one am very grateful for them.