From their magnificent capital at Alexandria, the Ptolemies oversaw a system largely put in place by the earlier Pharaohs to extract the wealth of the land. The last ruling Ptolemy was Cleopatra before the Romans took over Egypt and ruled it as a province.
The Ptolemies were a Hellenistic dynasty, ruling far-flung kingdoms in Greek fashion, and perennially at odds with other Hellenistic dynasties, such as the Antigonid dynasty. Each Ptolemaic ruler took a title along with his or her name; the first Ptolemy took the title Soter, or savior in Greek, to indicate that he had saved Egypt from collapse. The Ptolemaic rulers depended greatly on slave labor and mercenary warfare, dooming it in its eventual fight against Rome.
The Earth and Its Peoples A Global History, Bulliet et al, 2005.