oooh, abejaruco it's nice to see this map. but i must tell you, although the name is in tight connection with Slovenia- obviusly, it's not Slovenija but Slavonija, it's only one of the many regions that was once populated by Slovenians, nowadays, Slavonija lies in the hands of those...Croats!!!
it actually isn't Slavonia but Slovenijeh, it was named Slavonia later, during the period of so called "panSlavizm".
anyway, interesting that Slavonia made it to this map, really interesting, in this case, from observing the map, i'd say this "Slavonia" was meant just as an area populated by Slavs, from other maps i see Slovenijeh is much higher.