Why did a Roman Governor of Syria Have Any Jurisdiction Over Bethlehem Which Was Part of Judea--and not Syria?

In Luke 2, the scripture says that the Roman Caesar Augustus ordered everyone in the area to go to the home of their ancestors to be counted for purposes of taxation. At that time, Quirinius or Cyrenius was the Governor of Sysria, but Cyrenius was also a Roman. Because of that order, Joseph and Mary…