Dejan's son Jovan became a vassal of the Ottoman Empire after the Battle of Maritsa (1371), and Konstantin also acknowledged Ottoman suzerainty. Their province ("oblast") during the fall of the Serbian Empire was roughly located between the rivers Struma and Vardar and included territories of the modern countries of Bulgaria, Serbia and North Macedonia. According to Stojan Novaković, the province "spanned from Prince Lazar's border (between Kumanovo and Preševo and the Skopska Crna Gora ridge) and then much further towards the south, as it looks, to the wreath that in the south marks the border of the waterfall of the Dojran and Bulgarian lake".