Farmers of the Mumun Period began to use multiple cropping systems of agriculture some time after 1500 BC. This advance in food production irrevocably altered the subsistence systems of the Mumun and hastened the beginnings of intensive agriculture in the Korean Peninsula. Korea and adjacent areas of East Asia seem to have been a part of the domestication region of soybean ("Glycine max") between 1500 and 500 BC. Paddy-field agriculture, a system of wet-rice cultivation, was also introduced into the southern Korean Peninsula during this period.