The present study aims to outline the genetic makeup of the current population of the town of Yanga (Veracruz State, Mexico), the first Latin American settlement founded by African slaves in Mexico. For this purpose, we carried out the genetic characterization of 60 individuals from Yanga, analysing 15 autosomal short tandem repeats (STRs) and interpreting the results in the context of the admixed population known as Mexican mestizos. The genetic contribution from the three most important human groups in the current admixed Yanga population was calculated using Structure software. We detected a high percentage of Amerindian (48%) and European inheritance (44.7%), and a much less important African contribution (7.3%). These results were then compared with 10 other Mexican mestizo populations. The results fit the tri-hybrid model for admixture characterized by a high genetic contribution from Europeans and Africans in the north—though the African influence is lower—and a decreasing contribution from these two populations to the south and southeast. Conversely, the Amerindian component presents maximum values in the south and minimum values in the north. The Amerindian and European genetic traces are related to their ancestral settlements, but the African contribution can be explained by other parameters. To understand the current African genetic traces, we have to assume that there was a redistribution of these population groups and an important admixture phenomenon which led to the dilution of the African ancestral genetic pool. Furthermore, admixture was favoured by conditions that allowed individuals who intermarried to ascend in social status. These reasons would explain why despite the fact that Yanga was founded by black slaves, high levels of African ancestry are not found in the current population.