At first, people believed that sometime in the 7th and th century, Teotihuacán was attacked and burned by invaders The Toltecs might have invaded the city. More recent research shows, that the fire damage and looting seems to be limited to the structures and houses of the higher class or those considered elite. This evidence makes an uprising from the poor more likely than invasion. The invasion theory is also not as accurate, because excavation and restoration work started with the temples, and palaces. All these structures showed extreme fire damage. The archaeologists then concluded, that the whole city was most likely burned. The destruction seems to have been focused on structures along the Avenue of the Dead. Some statues seem to have been destroyed in a rather methodical way. The population in the city started to decline around the 6th century. This supports the hypothesis that there was unrest in the city. The decline in population is generally linked to drought and deforestation. These were linked to climate change, occurring in 535-536 A.D. There also seem to be more skeletons of young people, and more evidence of malnutrition in city in the 6th century.There is no conflict between the theories. Both increased warfare and internal unrest can also be effects of a general period of drought and famine.