The river is first mentioned in the Book of Genesis in connection with the meeting of Jacob and Esau, and with the struggle of Jacob with the angel.[4] It was the boundary separating the territory of Reuben and Gad from that of Ammon,[5] the latter being described as lying along the Jabbok.[6][7][8] The territory of Sihon is described as extending "from Arnon unto Jabbok" (Numbers 21:24), and it was reclaimed later by the King of Ammon.[9] Eusebius[10] places the river between Gerasa and Philadelphia.