Tsar is often mentioned in the Egyptian monuments as a frontier fortress on the Arabian side of what is now the Suez Canal, while another inscription mentions Gaza, and shows that the authority of the Minæan rulers extended to Edom, and came into close contact with Palestine and the surrounding tribes. Doubtless the protection of trade-routes was a main cause of this extension of fortified posts and wealthy cities, over such a wide extent of territory. From the most ancient times there has always been a stream of traffic between East and West, flowing partly by the Red Sea and Persian Gulf, and from the ends of these Eastern seas to the Mediterranean, and partly by caravan routes across Asia. The possession of one of these routes by Solomon in alliance with Tyre, led to the ephemeral prosperity of the Jewish kingdom at a much later period; and the wars waged between Egyptians, Assyrians, and Hittites were doubtless influenced to a considerable extent by the desire to command these great lines of commerce. Arabia stood in a position of great advantage as regards this international commerce, being a half-way house between East and West, protected from enemies by impassable deserts, and with inland and sheltered seas in every direction. Its southern provinces also had the advantage of being the great, and in some cases the sole, producers of commodities of great value and in constant request. Frankincense and other spices were indispensable in temples where bloody sacrifices formed part of the religion. The atmosphere of Solomon's temple must have been that of a sickening slaughterhouse, and the fumes of incense could alone enable the priests and worshippers to support it. This would apply to thousands of other temples through Asia, and doubtless the palaces of kings and nobles suffered from uncleanliness and insanitary arrangements, and required an antidote to evil smells to make them endurable. The consumption of incense must therefore have been immense in the ancient world, and it is not easy to see where it could have been derived from except from the regions which exhaled. "Sabæan odours from the shores of Araby the blest."