When Huns destroyed empires of Goths north of Black Sea, these and many other tribes were pushed to move westwards. During III. to V. centuries, territory of Bohemia was populated by many Germanic tribes - Goths, Skirs, Vandals, Heruls, Langobards. The romanised population on territory of nowadays Moravia and Slevania was pushed more nothern and eastern as the Germans invaded mostly from south east. Germans inhabited Bohemia exclusivelly and also South Moravia, whereas North Moravia and Slevania were still romanised.
Sometimes at the end of V. century, Slavic tribes appeared moving from northeast to Bohemia. They came and settled all the land eastern of river Saale, they penetrated south and stopped on Pellopones peninsula. On many places they met preceeding population - Germanic tribes, Romanic tribes etc. In nowadays Romania, Slevania and Veneda, the Slavs were assimiliated by Romanic population, on Balkane they were also assimilated by Greeks and Dalmato-Illyric settlement. In many other places they assimilated local Germanic tribes, namely in Bohemia and Moravia.
Havliš, Jan van Steenbergen, Ferenc