Perea (from Greek: peran (iordanou) ["beyond Jordan"]) was a district on the east side of the Jordan river whose northern border was south of Pella in the Decapolis and whose southern border was guarded by the frontier fortress of Machaerus.
In antiquity the region had belonged to Israel's bitter rivals, the kingdoms of Ammon and Moab, which were conquered by David [10th c. BCE]. After Solomon, during the time of the divided monarchy [9th-8th c. BCE], it was known as Gilead and was the homeland of Elijah. For about 600 years the region was lost to Israelite control, but was reconquered by Johanan Hyrcanus [ca. 120 BCE] and its inhabitants forcibly converted to Judaism. Augustus assigned Perea to Herod, who willed it to Antipas. This was the area of the activity of Johanan the Baptizer [according to John 1], including his imprisonment & execution at Machaerus [according to Josephus]. According to the synoptic gospels, Jesus took the Jordan valley road through Perea that ran from the southern end of the Sea of Galilee to the ford at Jericho on his way to Jerusalem.
Sources: Into His Own