I was recently talking to a Neopagan who made this claim, citing a wiki article. European paganism (aside from maybe the Vikings) was essentially extinct by that point as far as I know (I am not a medievalist, though, so I wouldn't know for sure). How true is this statement, or were there other pagan groups in the east that were targeted?
I only know a bit of danish history, so my reply is focused on that. I have to make this quick so it's going to be a short one.
European paganism was not extinct at the time of the first crusades.
To answer the question in the title: Yes. The Wends, who were slavic tribes living just south of The Baltic Sea had been exploiting the period of civil war in Denmark (1131-1157) to plunder around the coasts of Scandinavia. The Second Crusade started in the middle of this period (1147) and the two contending kings in Denmark, Svend and Knud, agreed on a truce and allied with the germans to convince the Pope to also target these pagan slavic tribes in the crusade. This first crusade against the pagans was ultimately a failure, but after the Battle of Grathe Heath and with the consolidation of power in Denmark under Valdemar the Great in 1157, pacifying the Wends became a big priority. This was just the start of many conquests against the pagans to the east. In 1169 Valdemar and bishop Absalon succeeded in taking the island of Rügen, just to name an example. The island was put under Roskilde diocese and the inhabitants were forced to convert to christianity.
Sources (in danish):
The book 'Danmarkshistorien i grundtræk' page 54-56. (Helge Paludan • Erik Ulsig • Carsten Porskrog Rasmussen Gerda Bonderup • Erik Strange Petersen Henning Poulsen • Søren Hein Rasmussen)