Bessus immediately proclaimed himself king of kings of Persia and adopted the throne name Artaxerxes (V). His self-proclaimed ascension was justifiable, since the satrap of Bactria, known as "mathišta", was the Persian noble next in the line of succession to the Persian throne. But since most of the Achaemenid Empire had already been conquered and Bessus only ruled over a loose alliance of those provinces not yet occupied by the Macedonians, historians do not generally regard him as a king.