Kulin (Serbo-Croatian Cyrillic: Кулин; d. c. November 1204) was the Ban of Bosnia from 1180 to 1204, first as a vassal of the Byzantine Empire and then of the Kingdom of Hungary, although his state was de facto independent.

[1] One of his most noteworthy diplomatic achievements is widely considered to have been the signing of the Charter of Ban Kulin, which encouraged trade and established peaceful relations between Dubrovnik and his realm of Bosnia.

[5][7] His rule is often remembered as being emblematic of Bosnia's golden age, and he is a common hero of Bosnian national folk tales.

[9] In 1183, Kulin Ban led his troops with the forces of the Kingdom of Hungary under King Béla and the Serbs under Stefan Nemanja, who had just launched an attack on the Byzantine Empire.

Kulin replied to the Pope that he did not regard the immigrants as heretics, but as Catholics, and that he was sending a few of them to Rome for examination, and also invited that a Papal representative be sent to investigate.

Unconvinced, the Pope sent his legates to Bosnia to interrogate Kulin and his subjects about religion and life, and if indeed heretical, correct the situation through a prepared constitution.

[15] Even today Kulin's era is regarded as one of the most prosperous historical eras, not just for Bosnian medieval state and its feudal lords, but for the common people as well, whose lasting memory of those times is kept in Bosnian folklore, like an old folk proverb with significant meaning: "Od kulina Bana i dobrijeh dana" ("English: Since Kulin Ban and those good old days").