The term 'Pony Indian American' refers to the CAYUSE people, a Native American tribe located in the Pacific Northwest region of the United States. The CAYUSE are known for their horsemanship and were among the first Native Americans to acquire horses from the Spanish. They are also known for their involvement in the Whitman Massacre, an event in which a group of CAYUSE attacked a mission established by Marcus and Narcissa Whitman in 1847.