Thailand province boundary data: geoBoundaries gbOpen THA ADM1, boundary year 2017, published Dec 12 2023.
Source: OpenStreetMap, Wambacher via geoBoundaries (William & Mary geoLab).
https://www.geoboundaries.org/api/current/gbOpen/THA/ADM1/
https://www.openstreetmap.org/copyright
License: Open Data Commons Open Database License 1.0 (ODbL).
https://opendatacommons.org/licenses/odbl/1-0/
Original simplified geographic dataset: /data/thailand-provinces.geojson
Derived SVG coordinates / Thai labels: projection and rounding of the above data.
Province marker positions are approximate polygon centroids, not customer addresses.