What does Matthew 2:22 mean?

King Herod, known as Herod the Great, has died, and an angel of the Lord has directed Joseph to take Jesus and Mary back to Israel (Matthew 2:19–21). The dire threat has passed. Joseph, though, detects a new threat once he is back in the land. He learns that one of Herod's sons, Archelaus, rules over Judea which is where Bethlehem is located. The thought of living directly under the rule of Herod's son would have made Joseph nervous, for good reasons.

Instead of passing his kingdom over to one son, Herod divided it into three parts. With Rome's approval, he gave one part to each of three of his sons. Archelaus was given Judea, Samaria, and Idumea to rule on behalf of the Roman Empire. Archelaus was known to be ruthless and cruel, like his late father. Joseph's fear of settling under his reign was validated when he received one last direction from the Lord in a dream: to settle in the northern part of Israel, instead.

Northern Israel, including Galilee and Perea, was ruled by Herod Antipas, while Herod Philip ruled over Iturea, Trachonitis, and other areas. Joseph settled Mary and Jesus in Galilee, where he had lived previously and under the rule of the more reasonable Herod Antipas. In the meantime, Archelaus ruled so badly that he was banished from Israel in AD 6. He was replaced for a time by a procurator rather than one of Herod's sons. Jesus grew up in Galilee, though, under the reign of Antipas.