 The presence of these elements from the cultures of the Mexican Plateau was conjectured recently to have been a result of a mass migration to, or conquest of, the Mayan city by Toltec groups.However, recent studies suggest that they may have been the cultural expression of a prestigious and widespread political system during the Early Postclassic in Mesoamerica.Oasisamerican peoples, whose influence was marked primarily by commercial exchanges between the north and south of Mexico, had widespread contact with the other peoples of Mesoamerica in the Northern Hemisphere, leading to a unique style of building construction in the Americas.