The Late Period of ancient Egypt refers to the last flowering of native Egyptian rulers after the Third Intermediate Period in the 26th Saite Dynasty founded by Psamtik I, but includes the time of Achaemenid Persian rule over Egypt after the conquest by Cambyses II in 525 BC as well. The Late Period existed from 664 BC until 332 BC, following a period of foreign rule by the Nubian 25th Dynasty and beginning with a short period of Neo-Assyrian suzerainty, with Psamtik I initially ruling as their vassal. The period ended with the conquests of the Persian Empire by Alexander the Great and establishment of the Ptolemaic dynasty by his general Ptolemy I Soter, one of the Hellenistic diadochi from Macedon in northern Greece. With the Macedonian Greek conquest in the latter half of the 4th century BC, the age of Hellenistic Egypt began.