For ten points, name this country led by kings including Kazimierz the Great and Boleslaw the Bold.
Bishop Jordan was responsible for converting this country to Christianity, and one king of this country issued the Third of May Constitution. One scholar from this country proposed that Russians were actually Finnish in ethnicity due to hydrological and geographical factors. Kings of this country (*)   included ones nicknamed "the wry-mouthed" and "the elbow-high", and this country was invaded in an event called the Deluge. This country's nobility had a liberum veto, which paralyzed its government in several key situations. This country's first episcopal see was established by King Mieszko at Gniezno, and this country's duchy of Mazovia invited the Teutonic Knights to participate in the Baltic Crusades. For ten points, name this country led by kings including Kazimierz the Great and Boleslaw the Bold.
Bishop Jordan was responsible for converting this country to Christianity, and one king of this country issued the Third of May Constitution.
Poland