Original: The Duchy of Saxe-Weimar-Eisenach ( ) was created in 1809 by the merger of the Ernestine duchies of Saxe-Weimar and Saxe-Eisenach , which had been in personal union since 1741 , when the Saxe-Eisenach line had died out .
Simplified: The two duchies had shared the same ruler since 1741 , which is when the Saxe-Eisenach line had died out .