Seafaring contacts between Iran and China via South and Southeast Asia—i.e., the Indian Ocean trade along the Maritime Silk Road—appear to have been well-established by the fijirst century CE. The Southwest or summer monsoon winds and rains from June and July through September and October blow from southwest to northeast, propelling ships from the Persian Gulf coastline over the Arabian Sea, down the west coast of India, to Serendib (Ceylon, Sri Lanka) and then across the Indian Ocean and Bay of Bengal through the straits of Southeast Asia and onward to the South China Sea. That was the path and time of year for journeys from Iranian to Chinese ports. The Northeast or winter monsoon winds and rains from November and December through March generally carried ships westward from China via Southeast Asia to the Maldive Islands and then northwestward to the Persian Gulf, although ships could also dock in the harbors along the southern shore of Serendib if cargo transfer or other mission goals warranted such a stop. The period of the Tang Empire (618–907) of China, which overlapped with the Sasanian Empire (224–651) and Umayyad (661–750) and Abbasid (750–1258) Caliphates of Iran was one of intense maritime trade. Pearls, coral, amber, ambergris (as a substrate for perfumes), ivory, tortoise shells, and spices were shipped between Persian Gulf and Indian Ocean ports such as Basra, Siraf, Muscat, Mantai, and Galle to Burma (Myanmar) and Siam (Thailand), then initially through the Sunda Strait and later through the Malacca (Melaka) Strait to Chinese ports like Canton (Guangzhou) and Nanjing. From China, the ships brought silks and porcelain, in particular, to the consumers of Southeast Asia, South Asia, and the Near East.