Ostsiedlung (German pronunciation: [ˈɔstˌziːdlʊŋ] , lit. 'East settlement') is the term for the early medieval and high medieval migration of Germanic peoples and Germanization of the areas populated by Slavic, Baltic and Uralic peoples; the most settled area is sometimes known today as Germania Slavica. Germanization efforts included eastern parts of Francia, East Francia, and the Holy Roman Empire and beyond; and the consequences for settlement development and social structures in the areas of settlement. Other regions were also settled, though not as heavily. The Ostsiedlung encompassed multiple modern and historical regions, primarily Germany east of the Saale and Elbe rivers, the states of Lower Austria and Styria in Austria, Poland and the Czech Republic, but also in other parts of Central and Eastern Europe.
The majority of Ostsiedlung settlers settled individually at various stages. Many settlers were encouraged and invited by the local princes and regional lords, who sometimes even expelled part of the indigenous populations to make room for German settlers.