The Mexican charro saddle evolved from the Spanish saddle brought to America by the conquistador Herman Cortes.
But the Spanish saddle did not have a horn. That feature is a Mexican invention. The Aztec Indians had taught settlers to braid and throw rope from the ground. They then adapted the skill for horseback work by building the iconic charro saddle horn recognized today.
Compared to a Western saddle, the charro saddle has a wider seat and a bigger horn, and it's constructed with leather strings holding it together. The Charro saddle is well suited for riding in the Western American mountains. The region has the same terrain and climate as Spain, where the saddle originally came from.