The Maya collapsed in 922 A.D. because the Toltec army sieged them. When the Maya collapsed they were suffering malnutrition and 80% of them had Anemia, a disease caused by a lack of iron. The land was being overfarmed from the mid 8th century onward for a long time, which may have been by the Toltecs, but the land was eroded and eventually the people left the land. Around 1225 there was mahogany pollen there, meaning it was forested, so it had to be left or intentionally forested by the Toltec. In around 950, the number of obsidian blades (used in sacrifice and worship) drops off, so the Toltecs probably made the Mayans give up their religion; but not completely, see the picture above of the temple, which is worshiping the Toltec god of dawn and Chac, the Mayan god of rain.
