The map is searchable using the search box and facets on the right. The numbers that appear in some of the icons within the map indicate the number of texts associated with that geographical region. Clicking on an icon displays the author and short title of the volume/s, and links to the record of each catalogue. The catalogues are classified and displayed according to place of publication. For technical reasons, the map used for the catalogue display is a modern one.
For an alternative approach, try the Timeline.