The Cohong, sometimes spelled or , a guild of Chinese merchants or hongs, operated the import–export monopoly in Canton (present-day Guangzhou) during the Qing dynasty (16441911). During the century prior to the First Opium War of 1839–1842, trade relations between China and Europe took place exclusively via the Cohong – a system formalised by an imperial edict of the Qianlong Emperor in 1760. The Chinese merchants who made up the Cohong were referred to as (行商) and their foreign counterparts as (literally "foreign traders"). In 1704, the Baoshang system was established. This system granted a number of Chinese merchants license to trade with Western merchants as long as they helped to collect duties from the Westerners, successfully aligning trading interests with the government's revenue collection. This was the predecessor for the later Cohong system. According to John Phipps, author of the 19th century Practical Treatise on the China and Eastern Trade, the merchant Poankeequa (潘启官) founded the guild in the 1790s, although Chinese historian Immanuel C.Y. Hsu cites an earlier date of 1720. Over time, membership of the Cohong fluctuated between five and 26 merchants authorized by the Chinese Central Government to handle trade, particularly rights to trade tea and silk, with the West. They were the only group at the time authorized to do this, making them the main controllers of all foreign trade in the nation. Within the city of Canton (Guangzhou, 广州) the Cohong were granted the Qing Empire's monopoly on foreign trade, overseeing the trade between western silver from the New World and valued goods from the Qing Empire Cohong merchant guilds therefore represented the primary link between the government of the Qing dynasty and the rest of the world. As Guangzhou represented the only official port of trade between the Qing trade network and European trading powers, the Cohong enjoyed a virtual monopoly over the trade with the west, and as such reaped the benefits of the Westerners' insatiable appetite for porcelain, silk, and most of all, tea.