Everybody assumes that it's a Jewish song. But like Hatikva (adapted from an Italian madrigal) and some other popular Jewish songs, it has its origins in a country and culture that is in no way Jewish.
That year, Germany entered the competition with a song praising the strength and sexual prowess of Genghis Khan, the 13th century Mongol conqueror. The song is titled Dschinghis Khan, by a band of the same name.
(A tip of the kippah to Jack Kustanowitz for bringing this story to our attention.)