After a settlement hiatus of around 200 to 300 years after the extensive migration of Germanic tribes from this area in the 4th / 5th centuries. Century probably took place around 700 AD (so far the oldest dendrodatum of a plank wall under the Slavic castle wall of Lübbenau ) and in the 8th century the settlement of Lower Lusatia increased by Slavic groups. Liubusua Castle, mentioned by Thietmar von Merseburg at the beginning of the 11th century, was previously regarded as the main castle of the Lusitzi . a. located near the present day Kosilenzien . However, recent research has credibly proven that Thietmar's descriptions refer to the castles on the Rauhen Furt north of Meissen directly on the Elbe and that Liubusua must be identical to the castle wall near Löbsal . This complex was conquered by Heinrich I in 932 and expanded again at the beginning of the 11th century. In this context, the Quedlinburg Annals report that Liubusua was in Daleminzien.
The Slavic inhabitants of today's Lower Lusatia are mentioned for the first time under the name of the Lunsizi in the Bavarian Geographers , a multi-layered spring, parts of which were created between the middle of the 9th and early 10th centuries. According to recent dendrochronological studies, the construction of castles began in the area of Niederlausitz around 870/880, at the latest by 890 AD . This development reached its greatest climax around 920 AD. It was undoubtedly a reaction to the increasing threat from the East Franconian Empire, which then in the well-known military campaign of King Henry I of 928/29 against the Heveller , Daleminzier and Bohemia and in 932 against the Lusitzi culminated in Lausitz itself. The Slavic elite was largely eliminated by Margrave Gero in the second half of the 10th century. Between 1002 and 1031 both Lower Lusatia and Upper Lusatia around Bautzen (the former tribal area of the Milzener ) were under Polish sovereignty.
The events of the 11th and the first half of the 12th century remain in the dark, only from the second half are more written sources accessible again. This time falls into the second phase of the medieval eastern settlement , when Slavic residents, together with German or Flemish settlers, established new villages in the old settlements and began clearing the previously undeveloped forest areas. Despite the assimilation processes that started with it, Lower Sorbian is still spoken in Lower Lusatia, a West Slavic language.
- Joachim Henning: Archaeological research on ramparts in lowlands. Lower Lusatia as a landscape of castles in eastern Central Europe in the early Middle Ages. In: Joachim Henning, Alexander T. Ruttkay (ed.): Early medieval castle building in Central and Eastern Europe. Conference, Nitra 7. – 10. October 1996. Habelt, Bonn 1998, ISBN 3-7749-2796-0 , pp. 9-29.
- Karl-Uwe Heussner, Thorsten Westphal: Dendrochronological investigations on wood finds from early medieval castle walls between the Elbe and the Oder. In: Joachim Henning, Alexander T. Ruttkay (ed.): Early medieval castle building in Central and Eastern Europe. Conference, Nitra 7. – 10. October 1996. Habelt, Bonn 1998, ISBN 3-7749-2796-0 , pp. 223-234.
- Felix Biermann : Slavic settlement between the Elbe, Neisse and Lubsza. Archaeological studies on settlement and material culture in the early and high Middle Ages. Results and materials for the DFG project "Teutons - Slavs - Germans". Habelt, Bonn 2000, ISBN 3-7749-2988-2 ( University research on prehistoric archeology 65 = writings on the archeology of Germanic and Slavic early history 5), (also: Berlin, Humboldt-Univ., Diss., 1997).
- Joachim Henning: The Slavic settlement area and the Ottonian expansion east of the Elbe. Event history - archeology - dendrochronology. In: Joachim Henning (Ed.): Europe in the 10th century. Archeology of a New Age. International conference in preparation for the exhibition "Otto the Great, Magdeburg and Europe". von Zabern, Mainz 2002, ISBN 3-8053-2872-9 , pp. 131-146.
- Günter Wetzel : Germans - Slavs - Germans in Lower Lusatia. In: Report of the Roman-Germanic Commission. 83, 2002, , pp. 206-242.
- Ralf Gebuhr: Jarina and Liubusua. Cultural-historical study on the archeology of prehistoric castles in the Elbe-Elster area. Results and materials for the DFG project "Teutons - Slavs - Germans". Habelt, Bonn 2007, ISBN 978-3-7749-3459-7 ( Studies on the Archeology of Europe 6).
- Lunsizi, ciuitates XXX.