Following Yangshao culture, Central Plain Longshan culture came to exist in the late Neolithic Age (about 4,000 to 5,000 years ago) in the middle reaches of the Yellow River. During this period, various states emerged across the Central Plain, cities were constructed, and new bronze smelting technologies invented. As a result, elements of a civilization appeared, new organizational patterns for human society emerged, and early states took shape, giving rise to a sphere of cultural influence that centered on the Central Plain and functioned at different levels.