This map shows Sclavonia, Croatia, Bosnia and a part of Dalmatia, (the present-day territories of Croatia, Slovenia, Bosnia, and parts of Serbia and Montenegro). There are many place names, woods, mountains, rivers and in the upper right corner we see the allegoric title cartouche and two mileage scales. In the upper middle field we sea three coat of arms. A ship in the lower left corner, which is on the Golf of Venezia, embellish the map. It is from his atlas, "Theatrum Orbis Terrarum, the title referring to the earlier atlas by Abraham Ortelius's 1570 work, generally considered to the world's first modern atlas.
Willem Janszoon Blaeu was a renowned geographer and publisher of the seventeenth century, when the Dutch dominated map publishing in Europe. Born in Arnhem, Jan was first exposed to the trade via his father, who was also a bookseller and publisher. In 1612, Jan married the daughter of Jodocus Hondius, who was also a prominent mapmaker and seller. His first maps date from 1616.
In the 1630s, Willem worked with his brother-in-law, Henricus Hondius. Their most successful venture was to reissue the Mercator-Hondius atlas. Jodocus Hondius had acquired the plates to the Mercator atlas, first published in 1595, and added 36 additional maps.
After Jodicus died in 1612, Henricus took over publication and Willem joined the venture in 1633. Eventually, the atlas was renamed the Atlas Novus and then the Atlas Major, by which time it had expanded to eleven volumes.
In 1629, the Hondius family (who owned Mercator's original copper plates) had a falling out and sold a large batch of their map plates at auction. Willem Blaeu swooped in and bought them.
Blaeu acknowledges that the map was originally engraved by Mercator with the credit line n the title cartouche, "Auct. Ger. Mercator". He kept the credit to Mercator as Mercaator was the most famous name in geography at the time (a good selling point), but he also acknowledges that is was republished by him at the bottom left with the words “Apud Guiljiel, Blaeu.”