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).
Saxons
Following the downfall of Henry the Lion (11291195, Duke of Saxony 11421180), and the subsequent splitting of the Saxon tribal duchy into several territories, the name of the Saxon duchy was transferred to the lands of the Ascanian family. This led to the differentiation between "Lower Saxony", lands settled by the Saxon tribe and "Upper Saxony", the lands belonging to the House of Wettin. Gradually, the latter region became known as "Saxony", ultimately usurping the name's original meaning. The area formerly known as Upper Saxony now lies in Central Germany.