Millions of Amerindians living in today's Amazonia altered the formerly poor soil through numerous mechanisms between 450 BCE and 950 CE. Soils were enhanced with charcoal from low-intensity fires used for cooking and burning trash, animal bones, broken pottery, compost, and manure through many human generations. The end product is Amazonian dark earth (ADE) or terra preta, which is extremely fruitful due to its high concentration of nutrients and stable organic matter formed from charcoal, which gives it its black colour.