Traditionally, rice was the forbidden commodity due to the fact that it was the main staple and crucial to stability of the kingdom. King Rama II allowed rice to be exported to China in some rice-surplus years. Chinese settler merchants played very important roles in the development of Siamese economy in the early Rattanakosin period. In the 1810s, the Chinese introduced the technology of sugar production leading to the establishment of numerous Chinese-owned sugarcane plantations in Central Siam. Crawfurd mentioned the Chinese sugarcane plantations in ฺBang Pla Soi, Nakhon Chaisi, Bangkok and Petriu. In 1822, Siam exported more than 8 million pounds of sugar. For the first time, the export-oriented marketization took over native trade of forest products. However, the profits of the these growing agro-industries were limited to the Chinese bourgeoisie and native elite class. The sugar industry remained as the major Siamese export well into the late nineteenth century. Burney Treaty and consequences: 1826–1855 By the reign of King Rama II, however, the Samphao Luang or Royal Junks became less profitable due to competition with growing private sectors. Since the Ayutthaya period in the fifteenth century, the Siamese royal court had monopolized foreign trades through the Phra Khlang Sinkha () or Royal Warehouse. All incoming foreign ships including European merchants should go through inspection by the Phra Khlang Sinkha and would subject to at least two duties; the general eight-percent tariff levied on merchandise goods and the Phasi Pak Reua or measurement duties that was based on the size of the ship. Crawfurd exemplified the situation in 1822 by narrating a commercial venture of British merchant brig Phoenix that brought goods from British India with the value of 24,282 ticals. Phoenix was subjected to multitudes of duties including 1,499-tical (equivalent to baht) measurement duties for ship size, 2,906 ticals for import duties and 6,477 ticals for export duties. These duties had been a major source of revenue for royal court. Moreover, Phra Khlang Sinkha would haggle and bargain for suppressed prices as foreign merchants could not trade 'restricted goods' directly with the private Siamese. Government-restricted goods in early nineteenth century included bird's nest, sappanwood, tin, peppers, timber, Malabar cardamom, lead, ivory and Hanbury's garcinia. When the British arrived in the 1820s, they saw traditional royal monopoly as a hindrance and implied that free trade should be the better agreement. This culminated in the arrival of Henry Burney and