Is the process of tribal unions, among a large group or groups of Slavic peoples. Migrations of the Sclaveni occurred in a number of years, the first recorded Slavic migration happened in 577 AD. The second wave of Slavic migration was in 610 AD, towards the Balkan region of the Roman Empire. The sclaveni numbered well over 20 to 30 groups or tribes. Grand alliances occurred and autonomous Slavic realms had formed. Serbia The first recorded alliance in Serbia was brought about under King Vlastimirovic the Kingdom of Rascia had formed after the union of the Serbian Slavs. Macedonia Under the authority, guidance and by order of King Prebond an alliance of the sclaveni tribes occurred possibly in 612 AD or 613 AD, forming the Kingdom of Belzetia. Slavic unions also occurred in Dalmatia and Bosnia possibly earlier in 580 AD.