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).
History of Saxony-Anhalt
The Golden Bull of 1356 raised the Duke of Saxe-Wittenberg to the permanent rank of elector, with the right to participate in the election of the Holy Roman Emperor. Electoral Saxony, as his territory was called, was a relatively small area along the middle Elbe. Extending to the south of Electoral Saxony was the Margraviate of Meissen, ruled by the increasingly powerful house of Wettin. The margraves of Meissen acquired (13th–14th century) the larger parts of Thuringia, Lower Lusatia and the intervening territories, and in 1423 Margrave Frederick the Warlike added Electoral Saxony; in 1425 he became Elector Frederick I. Thus, Saxony shifted to east-central and east Germany from northwest Germany.