The Taiwan Dog is a breed of small or medium dog indigenous to Taiwan. These dogs are also known as the Formosan Mountain Dog, Taiwanese Canis, Taiwanese Native Dog (台灣土狗) or Takasago Dog (高砂犬). They are well-adapted to the uneven and thickly forested terrain of Taiwan, having become a semi-wild breed prior to the arrival of several colonial reigns and foreign powers. Notwithstanding these adaptations, Formosans retained the potential to be trained and are now used as hunting dogs, guard dogs, stunt dogs, rescue dogs, or simply as companions. Formosans are classified into one medium type and two small types.