Very intersting, as I mentioned in other posts.
I just must say that the 9th and 10th centuries are not the start of the Dark Ages, but rather their end: the Western Roman Empire fell in the 5th century and, normally, the Dark Ages are considered to be the (in Europe) 6th, 7th and 8th centuries: the period of the barbaric kingdoms up to Muslim, Magyar and Muslim invasions. Charlemagne, crowned Emperor c. 800, is rather the beginning of the end of the Dark Ages.
In fact, that seems more coincident with the other periods you mention: Renaissance and Modernity. The Carolingian period is a time of some impulse forward and the start of a new period: the not so "dark" Middle Ages in their full swing.
Note: I just checked Wikipedia and it calls the 9th century the start of the "Dark Ages". But in my own knowledge of History, the name has always been applied to the previous period. This may be a difference between the English and Latin concepts. In continental Europe at least: the 9th century marks the beginning of the end of the dark period, with new consolidated powers arising, some increase in trade and literacy, etc.
Wikipedia defines the "Dark Ages" as "from about A.D. 476 to about 1000". But it also mentions a "Carolingian Renaissance", which I believe is much more adquate to what Xena in Aries seems to mean.