 Although "Kaogongji" does not explicitly identify this model with any historical city, it has been traditionally associated with Chengzhou, a city built by the Duke of Zhou soon after the Zhou conquest of the Shang.The “Proclamation at Luo,” a chapter of the "Book of Documents", describes how the Duke of Zhou traveled to Luo (near the site of present-day Luoyang) to establish a secondary capital for the new Zhou dynasty, further solidify the Zhou receipt of the Mandate of Heaven, and relocate the former subjects of the defeated Shang.The imperial era of urban planning was marked by an attempt to extend imperial authority uniformly across China by creating an economic and political urban hierarchy.