What is "cohong"

The Cohong, sometimes spelled kehang or gonghang, was a guild of Chinese merchants or hongs who operated the import-export monopoly in Canton (now Guangzhou) during the Qing dynasty (16441911). During the century prior to the First Opium War of 1839, trade relations between China and Europe were exclusively conducted via the Cohong, which was formalised by imperial edict in 1760 by the Qianlong Emperor. The Chinese merchants who made up the Cohong were referred to as hangshang and their foreign counterparts yanghang (洋行, literally "ocean traders").