诺夫哥罗德共和国
Gregory IX endorsed the Northern Crusades and attempts to bring Orthodox Slavic peoples in Eastern Europe (particularly Pskov Republic and the Novgorod Republic) under the Papacy's fold. In 1232, Gregory IX requested the Livonian Brothers of the Sword to send troops to protect Finland, whose semi-pagan people were fighting against the Novgorod Republic in the Finnish-Novgorodian wars; however, there is no known information if any ever arrived to assist.