In Europe, there were more or less four regions that were majority Muslim. Bosnia and Herzegovina, which was currently under Austro-Hungarian Control, Kosovo, which had been under Serbian Control until its occupation by Austro-Hungary and its eventual surrender a week or two prior to Bruno's arrival in Germany.
There was also the European parts of the Ottoman Empire, mainly eastern Thrace, that were currently a Muslim majority. And finally, there was the independent Principality of Albania. Which at this time was in a state of total anarchy after its German prince abdicated the throne upon the start of the war.
His reasons for doing so were simple. Surrounded on all sides by hostile powers, he felt it was better to flee with his life, then wait to be invaded. Because of this, Albania was now enduring a lawless chaos, with multiple factions fighting in all areas of the small Balkan country for control over the land.