Re-united Anhalt was again divided in 1603 among Prince Joachim Ernest's sons into the lines of Anhalt-Dessau, Anhalt-Köthen, Anhalt-Plötzkau, Anhalt-Bernburg and Anhalt-Zerbst. His second son Prince Christian I took his residence at Bernburg. Christian's younger son Frederick established the separate Principality of Anhalt-Harzgerode in 1635, which existed until 1709. Prince Victor Amadeus of Anhalt-Bernburg inherited Anhalt-Plötzkau in 1665. Upon his death in 1718 his lands were further divided and the Principality of Anhalt-Zeitz-Hoym was created for his second son Lebrecht, which was reunited with Anhalt-Bernburg in 1812.
In 1806, the Act of the Confederation of the Rhine elevated it to a duchy and in 1812 the two parts of the territory were united. Since 1815, the duchy was a member of the German Confederation. In 1847, Anhalt-Köthen-Plötzkau fell to Anhalt-Bernburg.