Brother: Cleopatra And

Ancient historian: historian → but needs to be in English. So

Moving on to the key events section: "The Ptolemaic dynasty and the practice of sibling marriage. The ascension of Cleopatra VII and Ptolemy XIII to the throne. The power struggles and rivalry between Cleopatra and Ptolemy XIII. The arrival of Julius Caesar in Egypt and his role in the sibling rivalry." cleopatra and brother

This is getting complicated. Maybe for "were", use remained. Let's proceed. Ancient historian: historian → but needs to be in English