Answer
Magas, the stepson of Ptolemy, became the ruler of Cyrenaica, a region comprising present-day Libya and Cyrenaica, around 300 BCE. Ptolemy, a Macedonian general under Alexander the Great, established himself as the ruler of Egypt and founded the Ptolemaic dynasty. Magas' marriage to Berenice, Ptolemy's daughter, strengthened the political alliance between Egypt and Cyrenaica.