The trade which the Romans “opened” with India by the way of the Red Sea, was conducted by them with success for more than five centuries; but we learn from Cosmas that, but a short time before his travels, they had met with a new and powerful rival in the Sassanian rulers of Persia, who, having overthrown the Parthians, and restored the ancient faith and monarchy of Persia, made early and vigorous efforts to acquire a share in the lucrative commerce of India. Following in the course of the early Phœnicians, the Persians with their ships commenced anew this eastern trade with India, and, in return for the productions of their own country, received the precious commodities of Hindustan, conveying them up the Persian Gulf, and, by means of the rivers Euphrates and Tigris, distributing them through every province of their empire. Rome being then in its decline, a powerful rival, such as Persia, could hardly fail to injure, if not to entirely destroy, the commerce the merchants of Alexandria had for ages nurtured with so much care. Moreover, the voyage from Persia to India, being much shorter, and attended with fewer dangers, led to an increase of the intercourse between the two countries, which the Greek merchants of Alexandria vainly attempted to resist. Even then, if Cosmas be trustworthy, few Europeans visited the eastern part of India, but were content to receive thence its silk, spices, and other valuable productions, either by caravans or the agency of native vessels. About this period, China carried on the most prosperous trade of any of the nations of the East, both by land and sea. Her caravans passed through Asia and Tatary, and her merchants conducted an extensive business with the provinces bordering on the Caspian, and in some cases with the more distant nations to the west and the north. Four hundred Chinese vessels are said to have been seen in the port of Ormuz, at the entrance of the Persian Gulf, and China is stated to have then received ambassadors from all the countries of Asia, as well as from Constantinople, and the Khalif of Baghdad, thus holding a direct intercourse with the whole civilized world. The vessels of China, however, had ceased to repair to the Persian Gulf long before the Portuguese made their appearance in Calicut; but from the time of Cosmas to that of Marco Polo they appear to have shared with the Arabians and Persians the carrying trade of the East, and to have even extended their voyages to the remote island of Madagascar. [Sidenote: The Muhammedans, A.D. 622.]