Probably the Oxus, called by the Arabs "Gaihun." Rabad I, a contemporary of Benjamin, speaks of the land of Gurgan in his Sefer Hakabalah. The Nestorian Christians are probably here referred to.
It is interesting to compare this account with that of the Installation of the Egyptian Nagid (J.Q.R., IX, p. 717).
This is a well-known sage, whose name often occurs in the Talmud.
The Babel of Bible times was captured by Sennacherib; after stopping up a dam of the Euphrates, the country was placed under water and the city destroyed. Nebuchadnezzar restored the city; he also erected a magnificent palace for himself—the Kasr—also the Temple of Bel. Herodotus, Book I, chaps. 178-89, fully describes these edifices, and dwells upon the huge extent of the metropolis, which was estimated to have a circuit of fifty miles. Xerxes destroyed the city. Alexander the Great contemplated the restoration of Bel's Temple, but as it would have taken two months for 10,000 men merely to remove the rubbish, he abandoned the attempt. The ruins have been recently explored by Germans. The embankments which regulated the flow of the Euphrates and Tigris have given way, and at the present time the whole region round Babylon is marshy and malarious. In the words of Jeremiah, li. 43, "Her cities are a desolation, a sterile land, and a wilderness, a place wherein no man dwelleth."
The Valley of Dura mentioned in Daniel iii. is here referred to. See Dr. Berliner's Beiträge zur Geographie und Ethnographie Babyloniens; also Layard's Nineveh and Babylon, p. 469. Cf. Berachot, 57 b.