A stem duchy (German: Stammesherzogtum, from Stamm, meaning "tribe", in reference to the Franks, Saxons, Bavarians and Swabians) was a constituent duchy of the Kingdom of Germany at the time of the extinction of the Carolingian dynasty (death of Louis the Child in 911) and through the transitional period leading to the formation of the Ottonian Empire.
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.
[5] 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.
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.
The use of Stämme, "tribes", rather than Völker "nations, peoples", emerged in the early 19th century in the context of the project of German unification.
Friedrich Christoph Dahlmann in 1815 asked for unity of the German nation (Volk) in its tribes (in seinen Stämmen).
This terminology became standard and is reflected in the preamble of the Weimar constitution of 1919, reading Das deutsche Volk, einig in seinen Stämmen [...] "The German nation (people), united in its tribes (stems) ...".
Within East Francia were large duchies, sometimes called kingdoms (regna) after their former status, which had a certain level of internal solidarity.
Historian Herwig Wolfram denied any real distinction between older and younger stem duchies, or between the stem duchies of Germany and similar territorial principalities in other parts of the Carolingian empire: I am attempting to refute the whole hallowed doctrine of the difference between the beginnings of the West-Frankish, "French", principautés territoriales, and the East-Frankish, "German", stem-duchies.
[8] Arnulf continued to rule it like a king even after his submission, but after his death in 937 it was quickly brought under royal control by Henry's son Otto the Great.
[9] The Ottonians worked to preserve the duchies as offices of the crown, but by the reign of Henry IV the dukes had made them functionally hereditary.