The Ptolemies Were Greek Rulers in Egypt
The large empire Alexander the Great of Macedonia had conquered was too big for one successor. One general was entrusted with Macedonia, another Thrace, and a third Syria. One of Alexander's favorite generals, Ptolemy, was made governor of Egypt. The esteem was mutual as can be seen in Ptolemy's having Alexander's body brought for burial to Egypt where it was permanently interred at the city Alexander had founded and named after himself. It is possible to view this gesture more cynically, as a way for Ptolemy to grab power.
Alexandria was the Egyptian city Ptolemy made his capital. There he founded a museum and started collecting books for a library.
For more than 350 years the Ptolemies ruled Egypt. Ptolemy's son Ptolemy Philadelpus ruled after Alexander's general. It was Ptolemy Phladelphus who made the library at Alexandria the best in the world. Its books, made of papyrus, were in Greek or Latin. Ptolemy Philadelphus had the Jewish Bible translated into Greek for his library. He is also known for re-opening a canal between the Red Sea and the Nile providing access between the Atlantic and the Indian Ocean. This was important for the wheat trade that enabled Alexandria to become the richest city in the world.
The Ptolemies encouraged erudition. One of Alexandria's students first taught that the earth is round and another determined almost the exact diameter of the earth.
The most famous Ptolemy was Cleopatra. With the death of Cleopatra, the dynasty of the Ptolemies came to an end and Egypt became part of the Roman Empire.