From the 9th to 13th century, the Vietnamese traded ceramics and silks with regional powers such as China, Champa, Western Xia, Java among others. Further archeological evidence suggests that Muslim traders had lived in Hanoi from around the 9th to 10th centuries, based on Muslim ceramics found in the Old Quarter of Hanoi. However, from the 16th century, Confucianism was losing its influence on Vietnamese society and a monetary pre-capitalism economy began to develop. During the Lê–Mạc period, the state encouraged semi-industrial business and sea-traders, as the Vietnamese economy would mainly depended on them for the next 250 years. Cities such as Dong Kinh, Hội An and others grew quickly under rapid urbanization. They were later constrained when foreign nations saw them as an economic threat. During the 17th century, Vietnam's economy had reached its peak as the country was the third-largest economic power in East Asia and Southeast Asia. In the late 18th century, the economy suffered depression because of a series of diseases and disaster such as the Tay Son peasant rebellion which devastated the country. In 1806, Emperor Gia Long of the new Nguyễn dynasty imposed the "Sea Ban policy", which banned all Vietnamese overseas business and stopped Western merchants from entering Vietnam. This policy led to stagnation of the Vietnamese economy in the early-19th century, and contributed to Vietnam becoming a French colony. 1858–1975 Until the French colonization in the mid-19th century, Vietnam's economy had been mostly agrarian, subsistence-based and village-oriented. French colonizers, however, deliberately developed the regions differently as the French needed raw materials and a market for French manufactured goods, designating the South for agricultural production as it was better suited for agriculture, and the North for manufacturing as it was naturally wealthy in mineral resources. Though the plan exaggerated regional divisions, the development of exports—coal from the North, rice from the South—and the importation of French manufactured goods stimulated domestic commerce. The separation distorted the basic Vietnamese economy by overly stressing regional economic differences. In the South, while irrigated rice remained the principal subsistence crop, the French introduced plantation agriculture with products such as tea, cotton, and tobacco. The colonial government also developed some extractive industries, such as the mining of coal, iron, and nonferrous metals. A shipbuilding industry was begun in Hanoi; railroads, roads, power stations, and hydraulics works were constructed. In the South, agricultural development concentrated on rice cultivation, and, nationally,