Sayn-Wittgenstein-Sayn was a County of Rhineland-Palatinate, Germany, comprising the lands of the region of Sayn. It was created as a partition of Sayn-Wittgenstein in 1607, although it was not until the next year that it obtained fully the Countship of Sayn. The succession was never clear, leading to the annexation of the County by the Archbishop of Cologne. It was not until a treaty in 1648 by the end of the Thirty Years' War was it decided the county would pass to the sisters Ernestine and Johanette, under the regency of their mother Louise Juliane. They partitioned the County into Sayn-Wittgenstein-Sayn-Altenkirchen and Sayn-Wittgenstein-Hachenburg soon after.