Complex sentence: She became Queen of Pontus and the Bosporan Kingdom when she married Polemon I. Polemon I was previously widowed by his first wife and had no natural children, except for a stepson.
Split into simpler sentences: She became Queen of Pontus and the Bosporan Kingdom when she married Polemon. Polemon was previously widowed by his first wife and had no natural children, except for a stepson.