These are geojson files relevant to Roman history. Initially they are all derived from the Ancient World Mapping Center's set of CC-BY-NC licensed shapefiles. The data is downloadable from http://awmc.unc.edu/awmc/map_data/shapefiles/political_shading/ . The CC licensing of this data is described here: http://awmc.unc.edu/wordpress/map-files/ .
I don't think that anything I'm doing here creates any new copyright so the original licensing pertains. If you fork the files or otherwise redistribute them, you should point back to the AWMC.