The first period will be primarily Byzantines as playable fraction trying to fend of almost everyone after Justiantins successful conquest of africa, spain and Italy. As well as the rising of the arabs...(maybe arabs and parthians will be acceptable as interesting major fractions...)

The Second Period will be primarily conserned with centre on rebuilding after the great losses during the arab rising...and will probably end around 950...major player will be muslim fractions and byzans...+some barbarians etc...

While the last period will centre on the crusade up to 1204 when the fourth (or was it the fifth) crusade takes constantinople...Major player will be crusader nations...venedig, sicilians, several muslim fractions...