Besides question marks over the attribution, there has also been considerable debate over the figure captured in the painting itself. Is it one of Rembrandt's local portraits, or perhaps a historical figure from the past? To go back this far and accurately identify someone is a tricky task, and has not been completely confirmed.
The connection to Rembrandt helps to position this amongst the most prominent artworks from the Frick Collection, where this painting has remained since 1910. Henry Frick was a respected art collector whose possessions can now be found on display in New York.
Most agree that the items found within this portrait point towards a Polish influence, hence the name. The precise individual has been labelled as the likes of a family connection to Polish-Lithuanian Oginski family Marcjan Aleksander Ogiński or instead perhaps the Polish theologian, Jonasz Szlichtyng. Equestrian paintings were fairly infrequent in Dutch art during this period so there is not much to compare it to.
Some have put forward historical characters as potentially the figure found in this scene, but again with little clear concensus. Old Testament David, the Prodigal Son and the Mongolian soldier Tamerlane have all been mentioned.
The clothing is also fairly casual compared to most equestrian portraits of this period, normally depicting someone of power and strength. Here, Rembrandt's produces a more personal, less formal atmosphere. The one comparison that can be made from amongst the artist's own career is with that of the Portrait of Frederick Rihel that can be found at the National Gallery in London.