The recent research emphasis of western academic community is focusing on the Polycentric Urban Region (PURs) similar to the Yangtze River delta . The PURs is a special type of town-dense region.

• 类似于长三角这种多中心城市区域(Polycentric Urban Region,PURs)研究是新近西方学术界开始集中探讨的一种特殊类型的城镇密集地区。