Cleopatra was queen because she was descended from a long line of rulers in Egypt. She was the daughter of Ptolemy XII Auletes, who ruled from 80 to 51 BC. After her father's death, Cleopatra and her brother Ptolemy XIII became joint rulers of Egypt. However, Ptolemy XIII soon became the sole ruler, and Cleopatra was forced to flee Egypt. She returned in 47 BC with the support of Julius Caesar. Caesar defeated Ptolemy XIII and his forces, and Cleopatra became the sole ruler of Egypt.