A division of time in Andean/Peruvian South America, c 600-1000 AD, used to refer to the first imperialistic domination of area under the unifying forces of Tiahuanaco and Huari (Wari) cultures. It was the time of the first large-scale imperial expansions. During the first half of the Middle Horizon, in central Peru, the Huari came to control the highlands and possibly the coast. The remains of large groups of food-storage buildings in the Huari strongholds suggest military activity like that of the late Inca. Huari is closely linked in its art style to the monuments of the great site of Tiahuanaco, located on Lake Titicaca, Bolivia. Tiahuanaco expanded over the altiplano and adjacent regions of Bolivia, southern Peru, and northern Chile. The principal buildings of Tiahuanaco include the Akapana Pyramid, a huge platform mound or stepped pyramid of earth faced with cut andesite; a rectangular enclosure known as the Kalasasaya, constructed of alternating tall stone columns and smaller rectangular blocks; and another enclosure known as the Palacio. They practiced the raised-field system of agriculture. Some Tiahuanaco effigy vessels have been discovered at Huari, but otherwise they seem to have been independent entities. In the second half of the Middle Horizon, the political and economic systems slowly collapsed. The decline of these two states was followed by a period of more localized political power. The Late Intermediate Period began about 1000 AD.