Ostsiedlung is the term for the Early Medieval and High Medieval migration of ethnic Germans and Germanization of the areas populated by Slavic, Baltic and Finnic peoples, the most settled area was known 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 such as Germany east of the Saale and Elbe rivers, the states of Lower Austria and Styria in Austria, Livonia, Poland, the Czech Republic, Slovakia, Slovenia, Hungary, and Transylvania in Romania.

Germans are the natives or inhabitants of Germany, or sometimes more broadly any people who are of German descent or native speakers of the German language. The constitution of Germany, implemented in 1949 following the end of World War II, defines a German as a German citizen. During the 19th and much of the 20th century, discussions on German identity were dominated by concepts of a common language, culture, descent, and history. Today, the German language is widely seen as the primary, though not exclusive, criterion of German identity. Estimates on the total number of Germans in the world range from 100 to 150 million, most of whom live in Germany.