Cassava, a root crop from which tapioca is made, was introduced in about 1935. The tubers may also be boiled and eaten as a vegetable or ground into flour. An important food in many tropical subsistence economies, cassava had never been significant in Thailand in the past because of the abundance of rice. Cassava developed into an important export item in the 1950s, and production continued through the 1970s and 1980s as external demand increased. Thai output of cassava root in 1984 was more than 19 million tons, second only to Brazil in world production. The main growing areas were Chon Buri and Rayong provinces, southeast of Bangkok, but substantial quantities were also grown in parts of the Northeast. In 1986 Thailand signed a 4-year tapioca trade agreement with the EEC calling for export of 21 million tons of tapioca during the 1987-91 period.