“Decapolis.” The Decapolis was a loosely associated league of ten cities (Deka means ten; polis means city), and is also the name of the area where these cities are located. By 200 B.C. the Greeks had occupied towns like Gadara and Philadelphia, and in 63 B.C. the Roman General Pompey liberated Hippos (Susita), Scythopolis (built on the ancient site of Beth-shean), and Pella from the Jews and gave them municipal freedom, allowing them to answer directly to the governor of Syria. About 1 B.C. they formed a league, even minting their own coins. Although the number of cities was probably ten at an early date, with time the number of cities changed. The Roman historian Pliny named the ten cities as Damascus, Philadelphia (modern Amman, Jordan), Canatha, Pella, Hippos, Gadara, Dion, Raphana, Gerasa (modern Jerash), and Scythopolis (ancient Beth Shean and the only city west of the Jordan River). In the second century A.D., Ptolemy named eighteen cities in the Decapolis, and another source mentions fourteen cities. Hence the number of cities varied from time to time.
The original Decapolis was settled by Greeks who migrated into the area shortly after the conquest of Israel by Alexander the Great. For the most part they either founded a city or moved into a city that did not have a large population and became the dominant influence there. Jesus is never mentioned as going into any specific city of the Decapolis. Nevertheless, he did minister in the area of Tyre, Sidon, and the Decapolis, so he well may have been in a Decapolis city (Mark 7:31), even though he primarily ministered to the “lost sheep of the house of Israel” (Matt. 15:24). Also, when word about Jesus and what he was doing reached the cities of the Decapolis, “large crowds from Galilee, the Decapolis, Jerusalem, Judea and the region across the Jordan followed him” (Matt. 4:25). Thus, the teachings and miracles of Jesus clearly caught the attention of the Greeks as well as the Jews.
“the region across the Jordan.” Since the list specifically mentions the Decapolis, the region across the Jordan River refers to Perea, the territory controlled by Herod Antipas, who was the son of Herod the Great by his wife Malthace (Herod had 5 wives in his lifetime). Herod Antipas married Herodias, who divorced his half-brother Herod Philip to marry him, and it was Herod Antipas who imprisoned John the Baptist in his castle at Machaerus when John confronted Herod Antipas and told him it was against the Law of Moses to marry his brother’s wife.