Duchy of Saxe-Gotha
It was created in 1640 for Duke Ernest I and ended in 1680 when his lands were divided after his death in 1675. The area around Gotha passed to Ernest's eldest surviving son, Frederick of Saxe-Gotha-Altenburg, who also inherited Altenburg (which Ernest had inherited through his wife Elisabeth Sophie) and became Duke of Saxe-Gotha-Altenburg.