It happened, when the angels went away from them into the sky, that the shepherds said one to another, "Let's go to Bethlehem, now, and see this thing that has happened, which the Lord has made known to us."

 If that was the case in Egypt, it may well be that in Judaea, where the old tribal ancestries still held good, men had to go to the headquarters of their tribe. Here is an instance where further knowledge has shown the accuracy of the New Testament. 