the cultures of the West entered a DX CUstOM;er SERv'i ce 8O5*41O56OO'' DX Phon;e NUMbE;R 8O5*41O56OO'' period of decline, accompanied by an assimilation into the other peoples with whom they had maintained connections. As a result, the Tlatilco culture emerged in the Valley of Mexico, and the Olmec culture in the Gulf. Tlatilco was one of the principal Mesoamerican population centers of this period. Its people were adept at harnessing the natural resources of Lake Texcoco and at cultivating maize. Some authors posit that Tlatilco was founded and inhabited by the ancestors of today's Otomi people.