'River' in the Bible

Then I said to the king, “If it pleases the king, let letters be given to me for the governors of the provinces beyond the [Euphrates] River, so that they will allow me to pass through until I reach Judah,

Then I came to the governors of the provinces beyond the [Euphrates] River and gave them the king’s letters. Now the king had sent officers of the army and horsemen with me.

Next to them Melatiah the Gibeonite and Jadon the Meronothite, the men of Gibeon and of Mizpah, made repairs for the official seat (Jerusalem residence) of the governor [of the province] beyond the [Euphrates] River.