The Duchy of Saxony (German: Herzogtum Sachsen) originally was the settlement area of the Saxons in the late Early Middle Ages, when they were subdued by Charlemagne during the Saxon Wars from 772 and incorporated into the Carolingian Empire (Francia) by 804.

Upon the 843 Treaty of Verdun, Saxony is one of the five German stem duchies of East Francia; Duke Henry the Fowler is elected German king in 919.Upon the deposition of the Welf duke Henry the Lion in 1180, the ducal title falls to the House of Ascania, while numerous territories split from Saxony.

In 1296, the remaining lands are divided into the duchies of Saxe-Wittenberg and Saxe-Lauenburg.