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The year was 342 BCE was a bad one for Artaxerxes III, who found himself with an empty treasury, several rebelling satraps, much of the manpower reserve badly mauled, and instability in the Royal Court.

First order of business for Artaxerxes was to gather the battered remnants of his army and march against Amarsin, a Babylonian rebel who had caused significant trouble for the Persian satrap there[1]. Amarsin dared not fight and was quickly captured and executed. Next he moved against Mithrobuzanes and Arsites, the rebel satraps of Cappadocia and Hellespontine Phrygia respectively. Artaxerxes III went and defeated many renegade satraps who caused great trouble for the empire and tried to establish a modicum of stability. In this he largely succeeded, and was ready to march against Egypt again in 338 BCE, hopefully to fill his treasury more. But he was poisoned by a eunuch named Bagoas, who raised Artaxerxes IV on the throne. Artaxerxes IV was poisoned 2 years after, for he had shown himself to have a will of his own and not to be a mere puppet.All the while, a new threat was slowly looming on the horizon, one which would spell the empire's doom.

Macedonia.

[1]- This character is fictional. I went by the line of thought that faliure in Egypt might cause more revolts. Mithrobuzanes and Arsites are real, however, and might have fought at Granicus in OTL.