Chinese in Torreón, Mexico and Indonesia

I am looking for information on the Chinese community in Torreón, Mexico. My paternal grandfather and his younger brother were there in the 1940s and all the way to the 70s in the case of the paternal granduncle, but they are both now deceased.

Separately, my mother's paternal grandfather went to Indonesia and lost contact with the family during World War II. Will get more details on names, dates and places from my parents to follow up on this. My mother had a high school teacher who has the same last name and is a distant relative. She grew up in Indonesia and I recall a story she told of her illiterate grandfather who employed people from our village (Kaiping in Guangdong province) by simply keeping thumbprints.

Any help greatly appreciated. Thanks.

vivian