The Shamo breeds are thought to derive from fighting chickens of Malay type brought from Thailand in the early part of the 17th century.
[citation needed] O-Shamo and Chu-Shamo are designations for different weight categories of large fowl, whereas the Nankin-Shamo is a bantam chicken.
The Ko Shamo (シャモ), unlike O-Shamo and Chu-Shamo, is merely an ornamental breed not used for cockfighting, although it is bred to be temperamental and show the spirit of a fighter.
[6] The Australian Poultry Standards have only one form of Shamo, which has a minimum weight of 3 kg.
[7] The American Poultry Association recognises the Shamo as a breed, both full-sized and bantam.