Chinese geometric puzzle, 1864, said to be an arbitrary formation based on anagram, etc. First element perhaps Chinese t'an "to extend," or t'ang, commonly used in Cantonese for "Chinese." Some suggest it is the name of the inventor, "but no such person is known to Chinese scholars" [OED]. Another theory involves the Tanka, an outcast aboriginal people of southern China, and Western sailors who discovered the puzzle from their Tanka girlfriends. Perhaps from an obscure sense of tram. The Chinese name is Ch'i ch'iao t'u "seven ingenious plan."