The derivation of the German people from a number of German tribes ("Deutsche Stämme; Volksstämme") developed in 18th to 19th century German historiography and ethnography. This concept of German "stems" relates to the early and high medieval period and is to be distinguished from the more generic Germanic tribes of Late Antiquity. A distinction was sometimes made between the "ancient stems" ("Altstämme"), which were in existence in the 10th century, and "recent stems" ("Neustämme"), which emerged in the high medieval period as a result of eastward expansion. The delineation of the two concepts is necessarily vague, and as a result the concept has a history of political and academic dispute.