The ten lost tribes are those tribes constituting the northern Kingdom of Israel (excluding Judah and Benjamin who constituted the southern Kingdom of Judah), which fell in 722 B.C.E. and its inhabitants were exiled to "Halah and Habor by the river Gozan, and in the cities of the Medes" (II Kings 17:6 and 18:11), but in general are believed to have disappeared from the stage of history. However, the parallel passage in I Chronicles 5:26 to the effect that the ten tribes were there "unto this day" and the prophecies of Isaiah (11:11), Jeremiah (31:8), and above all of Ezekiel (37: 19–24) kept alive the belief that they had maintained a separate existence and that the time would come when they would be rejoined with their brethren, the descendants of the Exile of Judah to Babylon. Their place in history, however, is substituted by legend, and the legend of the Ten Lost Tribes is one of the most fascinating and persistent in Judaism and beyond it. The belief in the continued existence of the ten tribes was regarded as an incontrovertible fact during the whole period of the Second Temple and of the Talmud. Tobit, the hero of the apocryphal book of his name, was depicted as a member of the tribe of Naphtali; the Testament of the 12 Patriarchs takes their existence as a fact; and in his fifth vision, IV Ezra (13:34–45) saw a "peaceable multitude... these are the ten tribes which were carried away prisoners out of their own land." Josephus (Ant., 11:133) states as a fact "the ten tribes are beyond the Euphrates till now, and are an immense multitude and not to be estimated in numbers." Paul (Acts 26:6) protests to Agrippa that he is accused "for the hope of the promise made unto our fathers, unto which promise our twelve tribes, instantly serving God, hope to come," while James addresses his epistle to "the twelve tribes which are scattered about" (l:l). The only opposing voice to this otherwise universal view is found in the Mishnah. R. Eliezer expresses his view that they will eventually return and "after darkness is fallen upon the ten tribes light shall thereafter dwell upon them," but R. Akiva expresses his emphatic view that "the ten tribes shall not return again" (Sanh. 10:3). In consonance with this view, though it is agreed that Leviticus 26:38 applies to the ten tribes, where R. Meir maintains that it merely refers to their exile, Akiva states that it refers to their complete disappearance (Sifra, Be-Hukkotai, 8:1).

Their inability to rejoin their brethren was attributed to the fact that whereas the tribes of Judah and Benjamin (the Kingdom of Judah) were "scattered throughout the world," the ten tribes were exiled beyond the mysterious river Sambatyon (Gen. R. 73:6), with its rolling waters or sand and rocks, which during the six days of the week prevented them from crossing it, and though it rested on the Sabbath, the laws of the Sabbath rendered the crossing equally impossible. According to the Jerusalem Talmud, however (Sanh. 10:6, 29c), the exiles were divided into three. Only one-third went beyond the Sambatyon, a second to "Daphne of Antioch," and over the third "there descended a cloud which covered them"; but all three would eventually return. Various theories, one more farfetched than the other, have been adduced, on the flimsiest of evidence, to identify different peoples with the ten lost tribes. There is hardly a people, from the Japanese to the British, and from the Red Indians to the Afghans, who have not been suggested, and hardly a place, among them Africa, India, China, Persia, Kurdistan, Caucasia, the U.S., and Great Britain. Special interest is attached to the fantastic traveler's tale told by Aaron (Antonio) Levi de Montezinos who, on his return to Amsterdam from South America in 1644, told a remarkable story of having found Indians beyond the mountain passes of the Cordilleras who greeted him by reciting the Shema. Among those to whom Montezinos gave his affidavit was Manasseh Ben Israel, then rabbi of Amsterdam, who fully accepted the story, and to it devoted his Hope of Israel (1650, 16522) which he dedicated to the English Parliament. In section 37 he sums up his findings in the following words: The Sambatyon is a legendary river across which part of the ten tribes were exiled by the Assyrian king, Shalmaneser, and which rested on the Sabbath. The river is mentioned in the Targum Pseudo-Jonathan (Ex. 34:10): "I will take them from there and place them on the other side of the Sambatyon River." The rabbis declared that the ten tribes were exiled three times: once beyond the Sambatyon River, once to Daphne of Antioch, and once when the divine cloud descended upon them and covered them (TJ, Sanh. 10:6, 29c; Lam. R. 2:9; cf. Gen. R. 73:6). The first ascription of miraculous qualities to this river is found in the Talmud. When Tinneius Rufus asked R. Akiva how he could prove that the Sabbath was divinely ordained as the day of rest, he replied, "Let the River Sambatyon prove it" (Sanh. 65b). It was unnavigable on weekdays because it flowed with strong currents carrying along stones with tremendous force, but it rested on the Sabbath (Gen. R. 11:5). These passages give no indication as to the supposed location of the river or of the origin of its name. The only inference that can be drawn from them is that it was located in Media. The most extensive description of both its name and locality is given by Nahmanides (to Deut. 32:26). He identified the river with the River Gozan of the Bible (e.g., II Kings 17:6), explaining the name (on the basis of Num. 11:31) as meaning "removed," i.e., the ten tribes were "removed" from the rest of their people. Nahmanides also held that its name derived from its Sabbath rest since Sabbat was the local word for the Sabbath.

הספר "מציאת עשרת השבטים" בשם חדש.