The Slavs established a foothold in the Czech lands during the Great Migration, initially coming under Avar control in the 6th century and participating in Avar raids throughout Central Europe. Around 623, Samo, a Frankish merchant, unified Slavic tribes across Bohemia and Moravia into the first known Slavic political union, Samo’s Realm. His leadership enabled the Slavs to resist both Avar and Frankish threats, culminating in the significant Slavic victory over Frankish forces at the Battle of Wogastisburg. However, Samo’s realm disbanded after his death in 658, and the Avars regained influence, settling on the Danube and exacting tribute from Slavic communities.
By the 8th century, fortified Slavic settlements and a warrior elite emerged, marking the rise of local power centers. Charlemagne’s campaigns in the late 8th century finally destabilized the Avar Khaganate, allowing the Slavs more autonomy. In this new context, Moravia became a prominent Slavic center by the early 9th century. The unification of Moravian and Nitra territories under Mojmír I laid the groundwork for Great Moravia, the first significant Western Slavic state.
Map of Europe in 900, showing Great Moravia and its neighbors. © Toshko Vihrenski
Mojmír's successor, Rastislav, further expanded Moravian influence and resisted Frankish dominance by inviting Byzantine missionaries Cyril and Methodius in 863 to promote Christianity and literacy in Old Church Slavonic. Rastislav’s nephew, Svatopluk I, strengthened Moravia’s ties with the papacy, expanding the realm to its zenith in the late 9th century. However, internal strife and Magyar invasions fractured the kingdom after Svatopluk's death, leading to the eventual collapse of Great Moravia by 907. This pivotal era set the stage for Czechia’s later development, grounding it in Slavic traditions and Christian literacy.