On page load, the visualization populates its blank SVG canvas with a horizontal dendrogram derived from a nested JSON dataset of world regions and countries. The tree layout recursively positions each node in a hierarchical branching pattern, with links drawn as smooth horizontal curves. The layout uses d3.tree() and d3.hierarchy() to process the data, while d3.linkHorizontal() generates the path coordinates. The code author uses D3 v5 within a React framework, though the direct SVG rendering bypasses React and relies on raw DOM selection.