Possible meanings are 1) the word "throne" is a metonym for "the place in which the governor had his throne" or "towns over which the governor ruled" or "the place from which the governor ruled" or 2) the word should be translated "seat" and is a metonym for "the place where the governor lived." (See: [[rc://en/ta/man/jit/figs-metonymy]])
This is the name of the province that was west of the Euphrates River. It was across the river from the city of Susa. See how you translated this in [Nehemiah 2:7](../02/07.md). (See: [[rc://en/ta/man/jit/translate-names]])