This self-sufficiency was aggravated by the position of the country among several of the main routes of ancient trade. The masters of Mount Se’ir held the harbours of ‘Akaba, into which the gold ships came from Ophir. They intercepted the Arabian caravans and cut the roads to Gaza and Damascus. Petra, in the very heart of Edom, was in later times the capital of the Nabatean kingdom, whose commerce rivalled that of Phœnicia, scattering its inscriptions from Teyma in Central Arabia up to the very gates of Rome.[515] The earlier Edomites were also traders, middlemen between Arabia and the Phœnicians; and they filled their caverns with the wealth both of East and West.[516] There can be little doubt that it was this which first drew the envious hand of Israel upon a land so cut off from their own and so difficult of invasion. Hear the exultation of the ancient prophet whose words Obadiah has borrowed: _How searched out is Esau, and his hidden treasures rifled!_[517] But the same is clear from the history. Solomon, Jehoshaphat, Amaziah, Uzziah and other Jewish invaders of Edom were all ambitious to command the Eastern trade through Elath and Ezion-geber. For this it was necessary to subdue Edom; and the frequent reduction of the country to a vassal state, with the revolts in which it broke free, were accompanied by terrible cruelties upon both sides.[518] Every century increased the tale of bitter memories between the brothers, and added the horrors of a war of revenge to those of a war for gold.