It was the diplomatic system adapted by the states before the establishment of modern, permanent diplomacy in the 14th and 15th centuries. States were sending temporary representatives or missionaries to each other for specific missions. For the solution of problems, signing treaties, declaring their war or peace decisions, etc. rulers were sending their representatives. After the formation of modern diplomacy, states began to adapt professional and permanent institutions and instruments. The Ottoman Empire used ad hoc diplomacy until the end of 18th century. The reign of Selim III, who was closely following the developments in Europe, was a turning point in the adaptation of modern diplomacy. Especially with Mahmud II, the Ottoman Empire began to adapt the rules and institutions of modern diplomacy despite some shortcomings.