A hierarchical tree visualization displays the geographic structure of the World, Asia, and its subregions down to individual countries. The example renders a horizontal dendrogram using D3 v5, with the `d3.hierarchy` and `d3.tree` layouts computing node positions, while `d3.linkHorizontal` generates curved SVG paths for the links. Data is loaded from a local `data.json` file, and the SVG canvas is sized to the full viewport dimensions.