There is consensus that Mustay-Bey is based on an actual person, but this person itself is unknown. Various theories have been put forward,
Evliya Çelebi calls him Mustaj-Beg Hasumović; Mustafa Imamović connects the figure of Mustay-Bey to a Mustafa Hurakalović that lived during the 17th century.
Luka Marjanović notes that, according to legend, Mustay-Bey hails from the Lipovača tribe from
Mostar. Older Croat historians' works help in confirming Mustay-Bey's identity. Historical sources mention a Mustaj-Beg that, in 1556, was captured by a
Frankopan and later released, after a ransom of several thousand ducats was paid. Similarly, many songs in the Krajina region concern the theme of Mustay-Bey being captured and released, such as:
" and . Evliya Çelebi mentions how
Melek Ahmed-Pasha sent him to buy back a certain Mustay-Bey Hasumović that was captured by the forces of
Nikola IV Zrinski. He also mentions that, while he lived, songs about Mustay-Bey were already being sung. Mustay-Bey was most likely the highest authority in
Lika and Krajina at the time, as a frontiersman () and commander, who had his headquarters in
Udbina. Perhaps his importance was increased by the fact that, after the establishment of captaincies in Krajina, the captain of Bihać was the supreme authority over all other captaincies. In
Kosta Hörmann's collections a wife and a daughter named Zlatija are mentioned. Even though legend tells of Mustay being from Herzegovina, the figure was created in the Krajina and later transmitted to other parts of Bosnia, Herzegovina and
Sandžak. == Tales ==