Ceasar Augustus issued a degree that a cencus should be taken of the entire roman world. This was the first cencus that took place while quirinius was governed of Syria. And everyone went to his own town to register. So joseph also went up from the town of nazareth in galilee to judea, to Bethlehem the town of David because he belonged to the joust and line of David. He went there to register with mary who was pledged to be married to him and was expecting a child. While they were there the time came for the baby to be born..... Ha. That's what came to my head, honestly lol