Xiamen, which is actually an island linked to the mainland by a long causeway of road and railway, is, like Shenzhen, a Special Economic Zone. Xiamen is flush with Taiwanese investment. The local dialect, known as minnanyu, is nearly identical to the dialect spoken in Taiwan, and the nearest Taiwanese-controlled islands - Matsu and Quemoy (Kinmen) - are just a couple of kilometers (a mile, or so) off shore from Xiamen. Historically, Xiamen was established as a major seaport in the Ming Dynasty, in the seventeenth century to stem the southward influence of the Manchu Qing dynasty and restore the Ming rule. Xiamen was also an unofficial trading depot, doing a thriving under-the-counter business in silks with the Portuguese, Spanish and Dutch, until a British naval force stormed ashore after their victory in the first Opium War in 1841 and opened it up as a full Treaty Port. There is evidence today of its role as an international settlement in the surviving colonial architecture of parts of its skyline.