Bamboo containers like this are used to store opium tools by highland communities in northern Thailand. The tools may include knives of various shapes and sizes, scrappers and other opium related paraphernalia.Poppies are grown as a cash crop mainly by the Lisu, Lahu, Hmong, and Yao, and to a lesser extent the Karen and Akha. The opium produced from poppies has traditionally been used for medicinal purposes and has enabled these communities to buy more rice from lowland markets. Opium production has continued to be fuelled by external demand since it was introduced to China during the 19th century until today. The Karen, Akha, Lisu, Lahu, Hmong and Yao are ethnic minority groups who migrated into northern Thailand from the neighbourng regions during the mid 18th and 19th centuries.