At the start of the game, the Byzantines were known as Romania, and they called themselves Rhomaioi.

Turks - Saljuq Turks
Egypt - Ayyubid Caliphate, later Fatimid Caliphate
Russia - Kievan Rus, Novgorod Cnezate(sp?)
Hungarians - Kingdom of Hungary, with the capital at Buda (Budapest is made by Buda and Pesta)
Spain - Kingdom of Castille, Kingdom of Leon, Kingdom of Toledo
Moors - Almoravid Berber Caliphate, later Almohad Caliphate
Italy(Milan and Venice) - Republic of Venice, Milan, Genoa, Florence
Sicily - Norman Kingdom of Sicily (Palermo and Naples)