This example visualizes the hierarchical structure of Xinjiang’s administrative divisions and their populations using a vertical tree layout. Each node is a circle colored by its top-level prefecture, with links drawn via `d3.linkVertical` and text labels rotated vertically. The code uses `d3.hierarchy` and `d3.tree` to compute positions, `d3.scaleOrdinal` with `d3.schemeCategory10` for colors, and renders output as SVG. Population data comes from the embedded `xinjiang.json` file.