The Star
The wise men, or their correct title Magi, followed the star and arrived some 9 to 18 months after Jesus was born.
Background Reading:
Matthew 2:9-10
Magi follow the star
9 After they had heard the king, they went on their way, and the star they had seen in the east went ahead of them until it stopped over the place where the child was. 10 When they saw the star, they were overjoyed.