Herod Antipas was the ruler of Galilee and Perea. He had arrested John the Baptist (see 14:1–12). John was probably working in the area at this time.
When Jesus heard about this, he left Judea. This was near Perea, where Herod had John arrested. Jesus then went back to Galilee. Jesus left to avoid death before he could finish his mission of revealing God's Kingdom. Like Joseph's escape to Nazareth (Matthew 2:22–23), avoiding danger can also be part of God's plan and fulfill prophecy (4:14–16).