Cahokia began to decline after 1300 AD. It was abandoned more than a century before Europeans arrived in North America, in the early 16th century, and the area around it was largely uninhabited by indigenous tribes. Scholars have proposed environmental factors, such as over-hunting and deforestation as explanations. The houses, stockade, and residential and industrial fires would have required the annual harvesting of thousands of logs. In addition, climate change could have aggravated effects of erosion due to deforestation, and adversely affected the cultivation of maize, on which the community had depended.