The thing to remember is that the Ptolemies ruled Egypt by conquest and pushed cultural syncretism. If you browse a museum with an extensive Egyptian collection

The thing to remember is that the Ptolemies ruled Egypt by conquest and pushed cultural syncretism. If you browse a museum with an extensive Egyptian collection, the Greco-Roman period items have a noticeably different style and really stick out. Compare representations of, say, Serapis and Osiris. One of the many reasons Cleopatra VII was notable is she was the only Ptolemy to actually learn the Egyptian language.