Yes, we've decided the starting date will be 700 (I think the end-date was 900) and so far the factions (a BG map can be seen under "Нации" here) would be: Eastern Roman Empire, Bulgaria, Kuber Bulgarians, Khazar Khaganate, Avar Khaganate, Arab Khalifate and (South) Slavic tribes (plus some rebels, of course).