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).
Eastphalia
Eastphalia (; Eastphalian: "Oostfalen") is a historical region in northern Germany, encompassing the eastern "Gaue" (shires) of the historic stem duchy of Saxony, roughly confined by the River Leine in the west and the Elbe and Saale in the east. The territory corresponds with the southeastern part of the present-day states of Lower Saxony, western Saxony-Anhalt and northern Thuringia. Together with Westphalia, central Angria and Nordalbingia it was one of the four main Saxon administrative regions. It should not be confused with East Westphalia ("Ostwestfalen").