Lower Saxony once formed the political center of medieval Saxony. It was from here that the Ottonian Emperors ruled and where Henry the Lion challenged the authority of Emperor Barbarossa. The legacy of Henry the Lion lived on in the successor states of Lower Saxony in Braunschweig and later the Kingdom of Hannover. It is a land of half-timbered houses and royal splendor.
Though today it is mostly known for the giant factory city in Wolfsburg that produces cars for Volkswagen, it was the political locus of medieval Saxony. Though it did not survive WWII, the city of Braunschweig was the seat of power for the Welf dynasty that challenged the Hohenstaufen for supremacy in the empire.
My version of Lower Saxony is based around the Successor States of the Welf family, namely the Duchy of Braunschweig-Lüneburg, but also includes the lands of Saxe-Launenburg and several other minor states. This contrasts the modern state of Lower-Saxony, largely based on the borders of the post-Napoleonic Kingdom of Hannover. I excluded most of the settlements on the upper Leine, i.e. up to Göttingen, because, except for Göttingen, they fit better into the historical narrative of Eastphalia.