Opium was primarily known for its medicinal properties and used in miniscule quantities for certain types of medicines. The Chinese were well aware of the dangers of its addiction, and the Emperor had therefore forbidden its production and sale except for medicinal purposes. But western merchants in the mid−18th century began an illegal trade in opium. It was unloaded in a number of sea ports of south eastern China and carried by local agents to the interiors. By the early 1820′s, about 1000 crates were being annually smuggled into China. Fifteen years later, over 35000 crates were being unloaded every year. This meant that the Chinese became addicted to opium. People of all classes took to the drug - shopkeepers and peddlers, officials and army men, aristocrats and paupers. In 1839, it was estimated that 4 million Chinese had become opium smokers. Thus, China became a country of opium addicts.