A form of intensive agriculture widely used in the Basin of Mexico during the early 1st millennium ad, often referred to as ‘floating gardens’. Chinampa were constructed by cultivating large mats of floating plants in deep water and then moving them to where cultivation plots were required on mud flats and swampy areas where several were stacked one on another to create a thick foundation layer. Canals were dug around three or four sides to facilitate drainage and provide mud and silt which was then spread on top of the mats. Waste from nearby settlements was added to the raised beds to give additional fertility. Each chinampa was about 10 m by 110 m and they were usually constructed on a regular grid pattern. Chinampas were used to grow staple root, vegetable, grain, and fruit crops and were kept in production all year round. It has been reported that, in ad 1519, 10 000 ha of chinampa supported about 100 000 people.