Various Mesoamerican civilizations used human feces to fertilize their crops. The Aztecs, in particular, are well known for their famous chinampas, artificial islands made of mud and human waste used to grow crops that could be harvested up to seven times a year. Current research has placed the origins of chinampas in an Aztec town of Culhuacan in the year 1100 C.E.[6] They were constructed by first fencing an area between 30 m x 2.5 m and 91 m x 9 m, using wattle.[7][8] Then filled in with mud, sediment, feces and decaying vegetation.