The canals of Lake Xochimilco were initially created along with artificial agricultural plots called chinampas. Chinampas were invented by the pre-Hispanic peoples of the region around 1,000 years ago as a way to increase agricultural production. On the shallow waters of the lakes, rafts were constructed of juniper branches. Onto these rafts floating on the water, lakebed mud and soil were heaped and crops planted. These rafts, tied to juniper trees, would eventually sink and a new one be built to replace it. Over time, these sunken rafts would form square or rectangular islands, held in place in part by the juniper trees. As these chinampa islands propagated, areas of the lake were reduced to canals. These “floating gardens” were an important part of the economy of the Aztec Empire by the time the Spanish arrived.