The Ascanians are named after Ascania (or Ascaria) Castle, which is located near and named after Aschersleben. The castle was seat of the County of Ascania, a title that was later subsumed into the titles of the princes of Anhalt.
The oldest known member of the House is Esiko, Count of Ballenstedt. He was first mentioned in 1036, and is assumed to have been a grandson (through his mother) of Odo I, Margrave of the Saxon Ostmark. From Odo, the Ascanians inherited large properties in the Saxon Eastern March.
Esiko's grandson was Otto, Count of Ballenstedt, who died in 1123. By Otto's marriage to Eilika, daughter of Magnus, Duke of Saxony, the Ascanians became heirs to half of the property of the House of Billung, former dukes of Saxony.
However, Albert inherited the Margraviate of Brandenburg from its last Wendish ruler, Pribislav, in 1150, and became the first Ascanian margrave. Albert, and his descendants of the House of Ascania, then made considerable progress in Christianizing and Germanizing the lands. As a borderland between German and Slavic cultures, the country was known as a march. In 1320 the Brandenburg Ascanian line came to an end.
After the Emperor had deposed the Guelph rulers of Saxony in 1180, Ascanians returned to rule the Duchy of Saxony, which had been reduced to its eastern half by the Emperor. However, even in eastern Saxony, the Ascanians could establish control only in limited areas, mostly near the River Elbe. In the 13th century, the Principality of Anhalt was split off from the Duchy, and later, the remaining state was split into Saxe-Lauenburg and Saxe-Wittenberg. The Ascanian dynasties in the two Saxon states became extinct in 1689 and in 1422, respectively, but Ascanians continued to rule in the smaller state of Anhalt and its various subdivisions until monarchy was abolished in 1918.