Jedlnia has always been associated with the Kozienice Forest. The name of the village comes from the fir forest, where fir branches are called fir. As a forest settlement, it probably existed around the first half of the 19th century. 12th century The situation of the village changed when Władysław Jagiełło issued a privilege in 1387 to its inhabitants, which gave them relief from many medieval burdens and obligations. From that moment on, the inhabitants became royal hunters, forest keepers and beekeepers.
This fact is commemorated by the statue of Władysław Jagiełło situated on the square opposite the church of st. Nicholas and St. Margaret. The monument shows the figure of the king of Poland, who points to a document granting the privileges of the inhabitants; the content of the document reads: "LORD OF GOD'S GRACE, THE KING OF POLAND, THE GREAT DUKE OF LITHUANIA, THE HERITAGE WILL START ... , UNDERGROUND, ORDINARY AND EXTRAORDINARY GRAINS, WE RELEASE FEES AND WORKS, AS THEY ARE CALLED, AND ALWAYS WILL RELEASE THROUGH THE PERSONAL GRACE OF OUR HIGHNESS ... TOMASZU APOSTOLE, R. P. 1387. The monument was erected in 2010, on the 600th anniversary of the Battle of Grunwald.