Traditionally, Moldavia had been a subject of the Kingdom of Poland, and later the Polish-Lithuanian Commonwealth. As the Ottoman influence grew in the 16th century, they had become more and more interested in the region. From the end of the 16th century and the beginning of the 17th century, the magnates of the Polish-Lithuanian Commonwealth intervened in the affairs of Moldavia, which the Ottoman Empire considered within its sphere of influence. Additionally, the Ottomans were aggravated by the constant raids of Cossacks, then nominally subjects of the Commonwealth, across the border into Ottoman territories. Another reason causing the war was the recent outbreak of the Thirty Years' War, and the request of support from the rebel leaders in Bohemia.