Samo founds the first recorded political union of Slavic tribes, known as Samo's empire (realm, kingdom, or tribal union), stretching from Silesia to present-day Slovenia, ruling from 623 until his death in 658.

According to Fredegarius, the only contemporary source, Samo was a Frankish merchant who unified several Slavic tribes against robber raids and violence by nearby settled Avars, showing such bravery and command skills in battle that he was elected as the "Slavic king."

In 631, Samo successfully defends his realm against the Frankish Kingdom in the three-day Battle of Wogastisburg.