Opium has been traded in Asia for many centuries and was first exported to China from Turkey and Arabia in the late sixth or early seventh century. For a thousand years, opium was traded on small scale across the Middle East and Central Asia to China, where is was used mainly in medicines. In the seventeenth century, however, the practice of smoking tobacco spread to China, and it was quickly discovered that mixing opium with tobacco and smoking it created a strong narcotic effect. The opium trade quickly grew, with hundreds of chests of the drug arriving in China annually by the beginning of the eighteenth century.
The initial major influencers of this new, vastly expanded opium trade at the beginning of the 1700s were the Portuguese, soon joined by the British, who had become the largest suppliers of opium to China by the 1770s. Both the Portuguese and the British found that they could export opium from India to China and sell it there at a large profit. Other Western powers joined the opium trade, including the United States of America, which dealt in Turkish opium, and several European countries which had Asian colonies where opium could be cultivated. However, the establishment first of the British East India Company, with its monopolies in Bengal, then of the British Empire in India, meant that the trade was soon dominated by Britain.