(Heb. Yabbok', יִבֹּק, according to Simonis, Onomast. p. 315, a pouring out, by Chaldaism from בָּקִק; otherwise, for יְאִבֹּק, a wrestling, from אָבִק, a coincidence that seems alluded to in Genesis 32:24; Sept. Ι᾿αβώκ, but Ι᾿αβώχ in Genesis 32:22; Josephus Ι᾿άβακχος , Ant. 4. 5, 2; Chald. יוּבְקָא, Targ.), one of the streams which traverse the Country east of the Jordan, and which, after a course nearly from east to west, between the districts of Merad and Belka (Seetzen, 18:427), falls into that river nearly midway between the Sea of Galilee and the Dead Sea, or about forty-five miles below the Lake of Tiberias, another outlet for. the water in time of freshets being situated a few miles higher up (Lynch, Exped. p. 253, and Map). It seems to rise in the Hauran mountains, and its whole course may be computed at sixty-five miles. It is mentioned in Scripture as the boundary which separated the kingdom of Sihon, king of the Amorites, or the territory of the Ammonites, from that of Og, king of Bashan (Joshua 12:1-5; Numbers 21:24; Deuteronomy 2:37; Judges 11:13; Judges 11:22); and it appears afterwards to have been the boundary between the tribe of Reuben and the half tribe of Manasseh (Numbers 21:6; Deuteronomy 3:16). The earliest notice of it occurs in Genesis 32:22, in the account of Jacob's mysterious struggle with Jehovah in its vicinity (south bank).
According- to Eusebius it was between Gerasa (Jerash) and Philadelphia (Amman). Origen:(Opera, 2, 43) says it was known in his day by the name Jmnbice (Ι᾿αμβίκη or Ι᾿αμβύκη ). "The stream is important in a geographical point of view, and a knowledge of its topography helps us to understand more easily some passages of Scripture. It was the boundary between the Amorites and the Ammonites. We are told that after the defeat of Sihon, king of the Amorites, at Jazer, ‘ Israel possessed his land from Arnon unto Jabbok, even unto the children of Ammon; for the border of the children of Ammon was strong (Numbers 21:24). The Jabbok, flowing in a wild and deep ravine through the Gilead mountains, formed a strong natural frontier for the bordering principalities. It would seem that at the Exodus the Ammonites possessed the country eastward and northward of the upper sources and branches of the Jabbok, and that Sihon amid Og occupied the whole region between the Ammonites and the Jordan, extending as far north as the Sea of Galilee (Joshua 12:2-8; Josephus, Ant. 4, 5, 2 and 3). The Israelites conquered Sihon and Og, and took their kingdoms; and the possessions of the three tribes, thus acquired, extended from the Dead Sea to Hermon; but they were not permitted to touch the territory of Ammon (Deuteronomy 2:37; Deuteronomy 3:16). About fifteen miles from the Jordan the Jabbok forks, one branch coming down from Jerash on the north, and the other from Rabbath-Amman on the south; these branches formed the western frontier of the Ammonites, dividing them from the Amorites, and subsequently from the Israelites (Reland, Pel. p. 103).
Previous to the Exodus the territory of the Ammonites was much more extensive, embracing the whole region between the Jabbok and the Amon; but the Amorites drove them out of that portion, and forced them into the mountains around the sources of the Jabbok, and into the plains eastward (Judges 11:13; Judges 11:22)" (Porter in Kitto, s.v.). It is now called the Zerka [or Wady Zurka] (from its "blue" color, Robinson's Researches, 3, Append. p. 326; but, according to Schwarz, Palest. p. 52, from a fortress of the same name on the caravan route from Damascus to Mecca). Its sources are chiefly on the eastern side of the mountains of Gilead, and it also drains a portion of the high plateau of Arabia beyond. In its passage westward across the plains it more than once passes under ground. The upper branches and tributaries are mere winter streams. At the point where the two main branches from Jerash and Ammon unite, the stream becomes perennial, and often, after heavy rain, is a foaming, impassable torrent. "The ravine through which it flows is narrow, deep, and in places wild. Throughout nearly its whole course it is fringed by thickets of cane and oleander, and the large clustering flowers of the latter give the banks a gay and gorgeous appearance during the spring and early summer" (Porter, Handbook for S. and P. p. 310). Higher up, the sides of the ravine are clothed with forests of evergreen oak, pine, and arbutus; and the undulating forest glades are carpeted with green grass, and strewn with innumerable wild flowers. The scenery along the banks of the Jabbok is probably the most picturesque in Palestine; and the ruins of town, and village, and fortress which stud the surrounding mountain sides render the country as interesting as it is beautiful. The water is pleasant, and, the bed being rocky, the stream runs clear (Burckhardt's Syria, p. 347; Irby and Mangles, Travels, p. 319; Buckingham, Palestine, 1, 109; Lindsay, 2, 123).