what relationship did the ottoman turks have with the early kingdoms of eastern europe?

??

They warred with them to seize control of more territory.

Generally not too great a relationship, because the Ottomans tended to invade Eastern Europe a lot, getting as far inland as Hungary. Here's a link to a map showing Ottoman conquests from 1481-1683. They also waged an unsuccessful campaign against the Italian states.

http://www.ottomansouvenir.com/img/Maps/Ottoman_Empire_1481-1683_map.jpg

Some of them were princeships that were paying taxes to the empire.

Like Moldovia for example.