Herod Archelaus was a son of King Herod the Great, a brother to Herod Antipas, and half-brother to Herod Philip. His mother was Malthace. Archelaus lived from about 23 BC to about 18 AD. After the reign of his father, he became ethnarch of Judah (or Judea), as well as Samaria, which is a part of the ancient land of Israel, and Edom, which also was known as Idumea.
His reign was so treacherous that it inspired the Jews and Samaritans, who otherwise were contentious enemies, to unite and lobby Rome to have Archelaus removed as leader over the region. Archelaus was sent into exile by Augustus, the Roman emperor at that time.
Even before he had been crowned as leader in 4 BC, Archelaus had already found a way to offend his subjects. He showed his incredible capacity for cruelty by slaying nearly 3,000 Pharisees in retaliation for a sedition that began when a Roman golden eagle emblem was removed and destroyed from the campus of the holy Temple in Jerusalem.
Aside from cruelty, Archelaus found other ways to offend. He violated Mosaic law by marrying the widow of one of his brothers, Alexander, even though his own wife was still alive, as was the previous husband of his new wife. This lead to criticism by John the Baptist.
Matthew mentions Archelaus in connection with Joseph, Mary and Jesus returning from their exile in Egypt. Joseph feared Archelaus and didn't want his family to be anywhere near him. So instead of settling his family in Bethlehem, which is near Jerusalem, he chose to settle in Nazareth, a remote town in the northern part of the Jewish homeland.