Sinai, a group of mountains in Arabia Pe-traea, in the southern portion of the peninsula of the same name, which projects between the two forks of the Red sea, the gulf of Suez separating it from Egypt on the west, and the gulf of Akabah from Arabia on the east. The peninsula of Sinai is triangular, about 140 m. in length from N. to S., and nearly the same in breadth at its widest portion. The northern portion is an arid and desert plain, with sand hills and mountains of small elevation; S. of lat. 29° 20' N. it rises into several ranges of mountains. There are numerous peaks, varying from 1,000 to over 9,000 ft. above the sea, divided by deep wadys or narrow sand valleys, except in the case of the Wady er-Rahah and the Wady esh-Sheikh, two wide valleys, the former separating the Jebel Ghub-sheh from the Jebel el-Fureiah, the latter the Jebel ed-Deir from the same mountain summit, and the two uniting in a wide plain in front of the Ras Sufsafeh, the abrupt northern termination of the Jebel Musa or Mount of Moses, the traditional Sinai. The summits of most historic and Biblical interest, beginning at the S. point of the peninsula, are the Jebel et-Turfa, a long low mountain sloping on either side to the sea and terminating in the low promontory of Ras Mohammed; the Jebel et-Tur, a series of summits of somewhat greater height surrounding the Jebel Musa, and separated from it by narrow steep wadys; the Jebel Katherin or Catarina, S. S. W. of the Jebel Musa, and forming the termination of the range known as the Jebel Humr; and the Jebel Musa, an isolated summit, with a plateau about 3½ m. long and nearly 1 m. in width, gradually descending toward the north.

The S. point, from which until recently it was supposed that Israel received the law, is 9,274 ft.' high, but is still overlooked by the higher peaks of Jebel Katherin and the Tinieh ridges, and the wadys in front of it are so narrow that the immense congregation could not have seen the summit of the mountain. To avoid this difficulty, Burckhardt, and after him Lepsius and some others, have attempted to demonstrate that the Jebel Serbal, which was sometimes called "the mount of God," lying some distance W. of the Jebel Musa, and having a valley of considerable extent, the Wady Feiran, at its N. face, is the true Sinai, with which Horeb, the Scriptural "mount of God," is so closely connected as to appear identical. But it seems that tradition rather points to that mountain as the site of Rephidim. The N. extremity of the Jebel Musa, called by the monks Ho-reb, and at its highest point Ras Sufsafeh, or "the mountain of the Willow," is supposed by Robinson and others to be the Sinai from which the law was dispensed.

It is divided from the Jebel ed-Deir on the east by a narrow valley, on one of the slopes of which the convent of St. Catharine is situated; but from the termination of the Ras Sufsafeh there open out the two wide valleys already mentioned, the Wady er-Rahah and the Wady esh-Sheikh, the only ones in the Sinaitic peninsula capable of containing the vast host of Israel. Opposite, in a succession of terraces, rises the Jebel Sona, the termination of the Fureiah ridge. The Ras Sufsafeh is 6,541 ft. high, and about 800 ft. lower than Jebel Musa, but it is the commanding point of the amphitheatre upon which it opens. There are three churches and three chapels on this mountain, all small and in a ruinous condition; and on the W. side, 2,000 ft below the summit, is the monastery, celebrated alike for its antiquity, its manuscript treasures, and the hospitality of its monks. The Arabs point out in the Wady er-Rahah the " hill of Aaron," the " pit of Korah," and the place where the molten calf was made. Carl Ritter suggested that Serbal was known before the giving of the law as " the mount of God," and that Pharaoh probably understood it as the mount to which they were going to sacrifice. Its distance and location well agree with this theory, for which early traditions give much ground.

Dr. Beke supposed the ancient Mt. Sinai to be a mountain E. of the meridian of the gulf of Akabah and valley of the Jordan. He was sent in 1874 on an expedition to establish his hypothesis. Advancing N. from the town of Akabah, by the route E. of the Jebel esh-Sherah, through the Wady el-Ithm, he found what answered his expectations in Mt. Baghir, also called Jebel en-Nur, or "mountain of Light." He bases his identification on an argument that, according to Scripture, the land of Midian, to which Moses tied, formed part of the east country, i. e., E. of the Jordan, and that he conducted the children of Israel there; and hence it follows that he crossed with them the gulf of Akabah, and not the present gulf of Suez. Dr. Brugsch also has recently advanced a theory which takes the Scriptural Mt. Sinai out of the so-called Sinaitic peninsula. He is of opinion that the Israelites marched along the Mediterranean coast, and that the disaster of the Egyptians occurred on the narrow strip of land which separates the sea from the Serbo-nian lake. There are many difficulties in the way of harmonizing these views with the details of the Biblical narrative.

As to Horeb in Scriptures, it seems probable that the whole desert of Sinai was so called (Heb. 'hareb, parched), and that the name was also specially applied to Sinai itself. From a period certainly not later than the first half of the 3d century, the caves of Jebel Musa, the traditional Mt. Sinai, were a refuge-of persecuted Christians; in the 4th century they were the resort of anchorites and ascetics, and these were repeatedly attacked and murdered by the Arabs. In the 5th and 6th centuries the monks of Mt. Sinai were represented in the great councils of the eastern church. During the period in which the Mohammedan power was at its height, the monks lived in fear and disquiet, often threatened and occasionally attacked. From the crusades onward they have held more peaceful possession, but with greatly diminished numbers and influence. - See Robinson, "Biblical Researches" (3 vols., Boston, 1856); Stanley, "Sinai and Palestine" (London, 1858); Wilson and Palmer, "Ordnance Survey of the Peninsula of Sinai" (London, 1872); Palmer, "The Desert of the Exodus" (London and New York, 1872); Ebers, Durch Gosen zum Sinai (Leipsic, 1872); and Maughan, "The Alps of Arabia" (London, 1874).