sentences:  The actual extension of the region is somewhat disputed as well as how it should be sub-divided.Geographically it has been defined as from the Sierra Madre Oriental to the Gulf of Mexico with the Sierra de Tamaulipas as the north border and the Cazones River as the south.It extends over the south of Tamaulipas, the southeast of San Luis Potosí, the northeast of Querétaro and Hidalgo and the extreme north of Veracruz and Puebla and a very small portion of Guanajuato over an area of about 32,000km2.