Here many caravans assembled, and thence diverged to their different destinations. Those destined for the East proceeded by way of Palmyra,[213] and to this day, the commercial road from Damascus to the Euphrates runs close to the ruins of that city. Seven days were occupied in the journey from Baalbek to Palmyra, four of them in passing through the desert which lay between that city and Emesa (Hems), another celebrated city of Syria. From Palmyra, other four days were required to reach Thapsacus,[214] where the caravan had the choice either of following the course of the Euphrates, or of passing through the plains of Mesopotamia. The southern, or rather the southern and eastern routes, passed through Palestine (where Joseph was sold to the caravan of Midianitish merchants) into Egypt, terminating at Memphis on the Nile. The eastern route diverged from it to Petra,[215] a place perhaps more celebrated than any other in the inland trade of ancient times. From Petra, there were two great routes to the East, both terminating in Gerrha on the Persian Gulf. Opposite to this place, and about fifty miles distant, lay the island of Tylos,[216] a settlement of the Phœnicians, as already stated. One of the routes lay along the line of the eastern shore of the Arabian Gulf, but at some distance from it, except where it touched Leuke Kome, and, most probably, Mecca also, till it reached Saba or Saphar, perhaps, as already suggested, the Ophir of Solomon, a distance of twelve hundred and sixty geographical miles from Petra, or a caravan journey of seventy days; thence the route lay through a great desert to Gerrha. The other route was almost a straight line through a more northern desert, from Gerrha to Petra, and was probably that by which Europe was first supplied with the produce of India. [Sidenote: Importance of Petra.] While Gerrha was the chief commercial city of Arabia to the east, Petra,[217] the capital of the Nabathæans, may be considered as occupying a similar position in the north-west of that country. A city equal in opulence to Gerrha, it constituted the chief western mart of the Arabian spices and frankincense, of which immense quantities were consumed in Egypt. Here important fairs were periodically held for the exchange of different commodities; and here the traders from the south met the merchants of Syria, and bartered the luxuries of the East for the manufactures of Tyre, and of the other cities of Phœnicia and Syria. According to the testimony of Ezekiel, the whole of this trade was carried on by barter, being an exchange of merchandise for merchandise, in which even the precious metals were included. [Sidenote: Intercourse between Syria and Babylon.] Many of the caravans of the northern route unloaded their merchandise on the banks of the Euphrates, whence it was shipped for Babylon and Susa, or conveyed through the canals, some of which were of considerable magnitude.[218] [Sidenote: Value of the trade of Babylon.]