Four species of Cinchona were cultivated for many years, primarily in Java and also in India and Ceylon (now Sri Lanka). Their bark was processed to obtain quinine, which is used in the treatment of malaria and for fever and pain, and quinidine, which is used mainly for cardiac rhythmic disorders. An explosion in demand for quinine among Europeans living in the tropics led naturalists to smuggle Cinchona seeds from South America to plantations in Asia in the 1850s and '60s and to conduct intensive research leading to new high-yield strains and improved processing methods.