In 1871, Wassaja was then purchased by an Italian photographer Carlo Gentile in Adamsville for thirty silver dollars at the age of 5 or 6 years old.

"I am a full-blooded Apache Indian, born around the year 1866... somewhere near Four Peaks, Arizona Territory", wrote Dr. Montezuma, introducing himself in a letter written in 1905 to the Smithsonian Institution.

Wassaja was brought to Adamsville, a mixed Anglo and Mexican village, and offered for 30 silver dollars to itinerant Italian photographer Carlo Gentile, who happened to be in the area for his ethnographic work on Native Americans.

[2]: 22–31 In the following years, Wassaja accompanied his adoptive father in his pioneering photographic and ethnographic expeditions in Arizona, New Mexico, and Colorado.

For a few months in 1872 and 1873, they joined the theatrical troupe of Ned Buntline and Buffalo Bill, where the boy Wassaja was featured as Azteka, the Apache-child of Cochise in the Wild West melodrama The Scouts of the Prairie in cities such as Chicago, St. Louis, Cincinnati, Louisville, Cleveland and Pittsburgh, while Gentile produced and sold promotional cartes de visite of the cast members.

Being regularly homeschooled by Gentile and attending public schools in Chicago (1872–1875), Galesburg (1875–1877), and Brooklyn (1877–1878), Wassaja had been revealed to be a committed and talented student.

Realizing that he needed a more permanent setting to complete his education, in the fall of 1878 Gentile asked for the assistance of the Reverend George W. Ingalls of the Indian Department of the American Baptist Home Mission Society.

Montezuma (or Monte as he was referred to by classmates)[4] also began his public activity in support of Native Americans' rights.

As early as 1887, Carlos Montezuma had been corresponding with Richard Henry Pratt, a staunch assimilationist and founder of the Carlisle Indian School in Pennsylvania.

In 1889 Montezuma traveled to reservations and provided services to Native Americans at Fort Stevenson in Dakota Territory.

In January 1893, Montezuma went to Colville Agency in the State of Washington, and finally, in July 1893 he traveled to the Carlisle Indian Industrial School in Pennsylvania.

In 1916 he started a monthly magazine titled Wassaja that he used as a platform to spread his views of the BIA and Native American education, civil rights and citizenship.