Original: In 1260 Albert bequeathed the duchy to his sons John I and Albert II, who gradually divided Saxony into the duchies of Saxe-Lauenburg and Saxe-Wittenberg with definite effect of 1296. Saxe-Wittenberg was recognized as the electorate of Saxony in the Golden Bull of 1356.
Simplified: Albert's sons divided Saxony into the duchies of Saxe-Lauenburg and Saxe-Wittenberg.