The paper examines the key problems of studying the first known source of the Slavic pre-state association – Samo's Empire (623-658): (1) The problem of sources telling about the Samo's Empire. It is shown that the only source containing original information about them is the “Chronicle of Fredegar”, while “Acts of Dagobert I” and “The Conversion of the Bavarians and the Carantanians” are strictly secondary sources in relation to it; (2) The problem of the origin of the Samo and the circumstances of its establishment among the Slavs. It is shown that regardless of the resolution of the issue of ethnic origin Samo, in its position, it was the elected Slavic prince, who performed the usual social and political functions for the Slavic princes; (3) The problem of the socio-political organization of the Samo's Empire and the question of the localization of its core. The hypothesis of understanding of the Samo's Empire is justified as a stepwise union of several Slavic ethno-political unions around one of them. The nucleus of the Samo's Empire is localized in the territory of modern Western and Central Bohemia and is regarded as a direct socio-political predecessor of the Ancient Czech Republic; (4) The question of the historical meaning of theSamo's Empire. It is shown that self-victory over the Franks stopped the Frankish onslaught on the Slavic lands for many decades and allowed them to develop steadily for a long time, which led to the creation of Karantania, Great Moravia, and then the Ancient Czech state. In the Appendix, for the first time in Russian, translations of fragments from the “Acts of Dagobert I” and “The Conversion of the Bavarians and the Carantanians” are published, narrating about the Samo's Empire.