 During this time, Moldavia was invaded repeatedly by Crimean Tatars and, beginning in the 15th century, by the Turks.In 1538, the principality became a tributary to the Ottoman Empire, but it retained internal and partial external autonomy.Nonetheless, the Polish-Lithuanian Commonwealth continued to strongly influence Moldavia both through national politics as well as on the local level through significant intermarriage between Moldavian nobility and the Polish szlachta.