The term Stammesherzogtum as used in German historiography dates to the mid-19th century, and from the beginning was closely related to the question of national unification. The term's applicability, and the nature of the stem duchies in medieval Germany, consequently have a long history of controversy. The overly literal or etymologizing English translation "stem duchy" was coined in the early 20th century. While later authors tend to clarify the term by using the alternative translation "tribal", use of the term "stem duchies" has become conventional.
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. The terms Stamm, Nation or Volk variously used in modern German historiography reflect the Middle Latin gens, natio or populus of the medieval source material.
Traditional German historiography counts six Altstämme or "ancient stems", viz. Bavarians, Swabians (Alamanni), Franks, Saxons, Frisians and Thuringians. All of these were incorporated in the Carolingian Empire by the late 8th century. Only four of them are represented in the later stem duchies; the former Merovingian duchy of Thuringia was absorbed into Saxony in 908 while the former Frisian kingdom had been conquered into Francia already in 734. The customary or tribal laws of these groups were recorded in the early medieval period (Lex Baiuvariorum, Lex Alamannorum, Lex Salica and Lex Ripuaria, Lex Saxonum, Lex Frisionum and Lex Thuringorum). Franconian, Saxon and Swabian law remained in force and competed with imperial law well into the 13th century.
The list of "recent stems" or Neustämme, is much less definite and subject to considerable variation; groups that have been listed under this heading include the Märker, Lausitzer, Mecklenburger, Upper Saxons, Pomeranians, Silesians, and East Prussians, roughly reflecting German settlement activity during the 12th to 15th centuries.