framework of imperial systems posited by American historian Alexander J. Motyl, the Aztec empire was an informal type of empire in that the Alliance did not claim supreme authority over its tributary provinces. It merely expected to pay tributes. The empire was also territorially discontinuous, i.e. land did not connect all of its dominated territories. For example, the southern peripheral zones of Xoconochco were not in immediate contact with the central part of the empire. The hegemonic nature of the Aztec empire can be seen in the fact that generally local rulers were restored to their positions once they conquered their city-state, and the Aztecs did not interfere in local affairs as long as the tribute payments were made. The form of government is often referred to as an empire, yet most areas within the empire were, in fact, organized as city-states (individually known as in Nahuatl, the language of the Aztecs). These were small polities ruled by a king or (literally "speaker", plurally ) from an aristocratic dynasty. The Early Aztec period was a time of growth and competition among altepeme. After the Nahuas formed the empire in 1428 and the empire began its program of expansion through conquest, the altepetl remained the dominant form of organization at the local level. The efficient role of the altepetl as a regional political unit was largely responsible for the success of the empire's hegemonic form of control. The term "Aztec empire" is actually modern and not one used by the Aztecs themselves. The Aztec realm was at its core composed of three Nahuatl-speaking city-states in the densely populated Valley of Mexico. Asymmetries of power elevated one of those city states Tenochtitlan above the other two over time. The "Triple Alliance" came to establish hegemony over much of central Mesoamerica, including areas of great linguistic and cultural diversity. The Nahuas performed administration of the empire through largely traditional, indirect means. Something of a nascent bureaucracy, however, may have been beginning to form over time, insofar as the state organization became increasingly centralized. Central administration Before the reign of Nezahualcoyotl (1429–1472), the Aztec empire operated as a confederation along traditional Mesoamerican lines. Independent altepetl were led by (lit., "speakers"), who supervised village headmen, who in turn supervised groups of households. A typical Mesoamerican confederation placed a (lit., "great speaker") at the head of several tlatoani. Following Nezahualcoyotl, the Aztec empire followed a somewhat