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
Otto I laid the basis of the organization of the Church in this territory by making the chief fortified places which he established in the different marks the sees of dioceses. The Byzantine emperors also aided much in bringing to Christianity the great Slavonic people, the Poles, who lived on the right bank of the Oder, as for a time the Polish country was under German suzerainty. The beginnings of Christian civilization among the Slavs were largely destroyed by the Slavonic rebellions in the years 980 and 1060. In 960 Otto I had transferred the ducal authority over Saxony to a Count Hermann, who had distinguished himself in the struggle with the Slavs, and the ducal title became hereditary in Count Hermann's family. This old Duchy of Saxony, as it is called in distinction from the Duchy of Saxe-Wittenberg, became the centre of the opposition of the German princes to the imperial power during the era of the Franconian or Salian emperors. With the death of Duke Magnus in 1106 the Saxon ducal family, frequently called the Billung line, became extinct. The Emperor Henry V (1106–25) gave the Duchy of Saxony in fief to Count Lothair of Supplinburg, who in 1125 became King of Germany, and at his death (1137) transferred the Duchy of Saxony to his son-in-law, Duke Henry the Proud, of the princely family of the Welf (Guelph). The hundred years of war waged by the family of Guelph with the Hohenstaufen emperors is famous in history. The son of Henry the Proud (died 1139) was Henry the Lion (died 1195), who extended German authority and Christianity into the present Mecklenburg and Pomerania, and re-established Christianity in the territories devastated by the Slavonic revolts. Henry the Lion refused to aid the Emperor Frederick I Barbarossa in his campaign against the cities of Lombardy in 1176, consequently in 1180 the ban of the empire was proclaimed against Henry at Würzburg, and 1181 the old Duchy of Saxony was cut up at the Diet of Gelnhausen into many small portions. The greater share of its western portion was given, as the Duchy of Westphalia, to the Archbishopric of Cologne. The Saxon bishops, who had before this possessed sovereign authority in their territories, though under the suzerainty of the Duke of Saxony, gained imperial immediacy subject only to the imperial government; the case was the same with a large number of secular counties and cities.