Country outlines: Natural Earth 4.1.0 via world-atlas 2.0.2, at 1:50m and 1:10m scales. Regional boundary lines: Natural Earth repository v5.1.2. Public domain.
Japan, South Korea and China municipal boundaries: geoBoundaries gbOpen, revision 9469f09, licensed under CC BY 4.0. Data is compressed, projected and converted to shared boundary lines for this map.
Japan ADM2 (2017): © OpenStreetMap contributors, via Wambacher. geoBoundaries source metadata lists CC BY-SA 2.0; OpenStreetMap database rights and licensing are described on its copyright page.
South Korea ADM2 (2020): geoBoundaries and citypopulation.de; underlying source licensed under CC BY 3.0.
China ADM2 (2017, county level): geoBoundaries, from the National Administration of Surveying, Mapping and Geoinformation of China via Revolutionary GIS; underlying source dedicated to the public domain under PDDL 1.0.
The prefecture or province containing each municipality: © OpenStreetMap contributors, ODbL 1.0, looked up through the Overpass API when the map data is refreshed.
Municipal boundaries currently cover Japan, South Korea and China. Other countries show regional boundaries where available. Administrative levels vary: Seoul is a metropolitan city, while its districts form the more detailed layer. China's detailed layer is the county level (counties, county-level cities and city districts), so prefecture-level cities such as Hulunbuir are not outlined on their own.
市级边界目前覆盖日本、韩国和中国；其他国家显示已有的省、州等行政边界。 首尔的市界属于上一级行政区，其区界会在进一步放大后显示。 中国的细分边界是区县级（县、县级市、市辖区），呼伦贝尔这样的地级市不单独勾出轮廓。 这些边界表示行政区划。
Japan's prefectures and municipalities are different levels: Kyoto Prefecture is distinct from Kyoto City. In Japan, South Korea and China, prefectural and provincial borders are drawn from the municipal boundaries themselves, so the two layers align exactly; Seoul's outline is the outer edge of its districts. Other countries show Natural Earth regional lines.
日本的府县与市町村属于不同层级，例如京都府与京都市不同。 日本、韩国和中国的府县、省级边界直接由市町村或区县边界组成，两层完全吻合；首尔的市界即其各区的外缘。 其他国家显示 Natural Earth 的省州边界。