Yes, its from Euratlas. They're nice looking maps, but rather inaccurate, eg in 700 AD the Antes did not exist. Yes, it has a nice picuture of Savia in 900AD, which would be Braslav's Greater Duchy. Thehistory of Pannonia region is more vague than others. From what I have understood: 

 *Initially Lower Pannonia referred to south of the Drava, ie "Croatian Pannonia". After Liutevid's revolt, Louis the German re-organized the Frankish eastern Marches (Carinthia, Lower Pannonia, Upper Pannonia, Carniola). He rotated the borders of L and U Pannonia 90'. Ie, the border line now ran through the Raab river in NW Hungary, so that it would fit the ecclesiastical borders b/w Salzburg and Passau. Upper Pannonia was what became Ostmark, ie northern Austria. Lower Pannonia is exactly where Balaton Principality is - ie b/w the Raab, Danube and Drava rivers according to Goldberg (who wrote a book on the rule of Louis the German). The New cambridge Medieval History extend this border to the Sava. So the rulers we know in the area are: 

 *Vojnomir- who heled the Franks in c. 800 against the Avars 
 * Liutevid (910-823) 
 * Ratimir sometime in the 830s, who was expelled by Ratbod. 
 Then nothing, no ruler mentioned. Perhaps during this the Savia (Croatia b/s Sava and Rava) was ruled by Ratbod directly, or maybe by Pribina and Kotsel from their center in Blatnograd. Not until 894, when Kotsel dies we here of Braslav, poor guy only got to rule for 5 years before those nasty Magyars came and caused trouble.