Chalky's parents were spanish speaking Blacks that lived in Mexico. He was raised amongst Mexicans. Plus he was born in Mexico. The fact is that he was the first fighter born in Mexico to win a title. However, I will say that when I studied at ITESO a University in Guadalajara I met Lebanese, Jews, and Germans that were born and raised in Mexico and for all purpose they were Mexican. They loved mariachi, the food, and they had the temperment of a Mexican. Considering this I believe that Chalky may actually be the first Mexican to win a title.
Baby Arizmendi won the NYSAC Featherweight title in 1934. He was Mexican. He fought Wright, too, beating him twice. Wright is one of those fighters who all the Hall of Famers beat, however, he is one himself. Great puncher.
According to the IBHOF, Wright was born in Durango State, Mexico, and won the world featherweight crown on September 11, 1941.
"Mexican" is a nationality, not an ethnicity. :thumbsup So your criteria is valid, but the factual accuracy depends on who actually was the first born in Mexico to win a world title.
Arizmendi was the first fighter born in Mexico to win a version of a world title, and Wright was the first to win a universally recognized world championship. Both remain among the better featherweights in history, and both remain among the better fighters that nation has produced