Upper Saxony
It was particularly to distinguish the lands from 'Lower Saxony', a concept which arose later in popular usage (though never enforced) as a term for the original Saxon lands in north and west Germany (where Low German dialects had spread), in what is now the state of Lower Saxony, as well as the adjacent Westphalian region, Holstein and the western part of today's Saxony-Anhalt north of the Harz range (Eastphalia).
Duchy of Saxony
The Saxon stem duchy covered the greater part of present-day Northern Germany, including the modern German states () of Lower Saxony and Saxony-Anhalt up to the Elbe and Saale rivers in the east, the city-states of Bremen and Hamburg, as well as the Westphalian part of North Rhine-Westphalia and the Holstein region () of Schleswig-Holstein. In the late 12th century, Duke Henry the Lion also occupied the adjacent area of Mecklenburg (the former Billung March).