Principality in eastern Germany, which in the 18th century lay between western Brandenburg in the Kingdom of Prussia and western Saxony but in the 19th century was entirely surrounded by Prussia. It stretched from lands to the north of the Elbe across to the lowest reaches of the Mulde and to a section on the lower Saale. There was also a detached portion lying on the northeastern edges of the Harz Mountains. The Principality was usually divided among branches of the family.
It had begun in the 11th and 12th centuries with the County of Ballenstedt, which was at the northeastern end of the Harz. Count Otto the Rich, who died in 1223, married Eilica, one of the heiresses of the last Billung Duke of Saxony, and through her he acquired some of the Billung lands in the region of the Elbe. His son, Albert the Bear, accumulated many territories and was the founder of Brandenburg. When he died in 1170, his lands were divided among his several sons, the youngest, Bernard, becoming Count of Anhalt. That name came from a castle in the Selketal, in the Harz south of Ballenstedt. Bernard soon acquired the County of Ballenstadt from a dead brother, but the name of Anhalt prevailed.
Bernard was made Duke of Saxony by the Emperor Frederick Barbarossa after the deposition of Henry the Lion in 1180. The lands that belonged to the Duchy were few, and made fewer by the advance of Denmark southwards in the late 12th and early 13th centuries, so that when Bernard died in 1212, his elder son, Henry, took the County of Anhalt, leaving the more distinguished title to his younger brother, on the principle that a County in the hand is worth a Duchy in the bush. Henry used the title of Prince of Anhalt from 1218.
When he died c.1252, Anhalt was divided amongst his three sons, the Princes of Anhalt-Aschersleben, -Bernburg and -Zerbst. There were various other divisions and rearrangements before 1570, when all the lines but one had either died out or given up their claims. The survivor, Prince Joachim Ernst, reigned in all Anhalt until his death in 1586, after which his sons ruled the Principality jointly. Joint rule brought its problems, and in 1603 the five Princes divided Anhalt between five lines: Dessau, Bernburg, Plötzkau, Zerbst, and Köthen.
The Anhalt Princes belonged to the Upper Saxon Circle.
The surviving Princes (of Dessau, Bernburg and Köthen) entered first the Confederation of the Rhine in 1807, as Dukes, and then the German Confederation in 1815. In 1863, the other two lines having died out, Anhalt was reunited under the senior (Dessauer) line, whose head took the title of Duke of Anhalt.
In the Weimar Republic Anhalt remained a separate state, but in Nazi Germany there was one Governor for Anhalt and Brunswick. At the end of the Second World War, Anhalt was included in the Soviet Zone of Germany and was united with Prussian Saxony to form the Land of Sachsen-Anhalt.