Jesus' birth date was determined long before any evidence for his existence had been discovered. Historians have always known when Jesus was born because the Gospels report it: "And Jesus increased in wisdom and stature, and in favor with God and men." His birth was observed by many people, including the magi who visited him after he was born. They saw the signs in the heavens that indicated that a king would be born in Israel and decided to go back to their countries to tell their rulers that someone great was born.