Its territory was part of the modern states of Bavaria and Thuringia.

However, because the two princes were still minors at the time, the country was at first ruled by Elector August of Saxony.

John Ernest soon withdrew and returned to his hunting lodge in Marksuhl.

When John Ernest died childless as well in 1638, the line of the Dukes of Saxe-Coburg-Eisenach ended and the country was divided between Saxe-Weimar and Saxe-Altenburg, the other two Ernestine duchies existing at that time.

Saxe-Coburg and Saxe-Eisenach would not again belong to a common state, until all Ernestine duchies merged to form Thuringia in 1920.