The World's Megacities by Region

East Asia hosts some of the largest urban agglomerations on Earth. Greater Tokyo, encompassing Tokyo, Yokohama, and surrounding prefectures, is generally regarded as the most populous metropolitan area in the world, with a population commonly cited near 37 to 38 million people. Shanghai and Beijing, China's two largest cities, have each grown past 20 million residents within their municipal boundaries, driven by decades of rural-to-urban migration and industrial expansion following China's post-1978 economic reforms. Seoul, together with the port city of Incheon and surrounding Gyeonggi province, forms a metropolitan area of roughly 25 million, concentrating around half of South Korea's entire population in a single urban region.