For many it might be a new information but there were even slavic vikings. The ties between western Slavs and scandinavians were quite close. Especially between Denmark and Poland. Daughter of polish ruler Mieszko I became a wife of king of Denmark and mother of Knut the Great - king of Denmark and England. Also most of weapons and armours which Polish wariors used in the 10th and in the begining of the 11th was made in Scandinavia. Some wariors from the area of modern Poland were even joining the vikings while many vikings served as mercenaries on the court of first polish rulers.
Especially interesting thing is the Jomsborg (today Wolin island and city) near the coast of Poland. A slavic settlement where the Danes build a fort became a home of famous Jomsvikings who were most feared wariors renowned for their honour and their courage. They were well known on the whole Baltic area and feared by all the vikings who were coming back home from long journays with their spoils. Altough some historians claim that they were slavic pirates, there are evidences in the scandinavian saga's that scandinavian element was strong if not dominant. In the 11th century majority of Jomsvikings became Vends (scandinavian word for Slavs). Finally they were invaded and slaughtered by the Danes, after raiding Denmark what made Danish king angry.

Today, on the island where 1000 years ago was famous Jomsborg every summer takes place the biggest event of this kind in Europe "Viking-Vendish Festival" where come thousands of vikings and slavic wariors from all the Europe to fight both on the land and on the water.

There is famous scandinavian Saga "KING OLAF TRYGVASON'S SAGA" about Jomsviking's unsuccesfull attempt to invade Norway from which comes famous quote:

"Eigi Eru Enn Allir Jomsvikingar daudhir"
("Not Yet Are All the Jomsvikings Dead")


From this Saga:
"The Jomsborg vikings assembled their fleet in Limafjord, from
whence they went to sea with sixty sail of vessels. When they
came under the coast of Agder, they steered northwards to
Rogaland with their fleet, and began to plunder when they came
into the earl's territory; and so they sailed north along the
coast, plundering and burning. A man, by name Geirmund, sailed
in a light boat with a few men northwards to More, and there he
fell in with Earl Hakon, stood before his dinner table, and told
the earl the tidings of an army from Denmark having come to the
south end of the land. The earl asked if he had any certainty of it.
Then Geirmund stretched forth one arm, from which the hand
was cut off, and said,
"Here is the token that the enemy is in the land."
Then the earl questioned him particularly about this army. Geirmund says it consists of Jomsborg vikings, who have killed many people, and plundered all around. "And hastily and
hotly they pushed on," says he "and I expect it will not be long
before they are upon you." On this the earl rode into every
fjord, going in along the one side of the land and out at the
other, collecting men; and thus he drove along night and day. He sent spies out upon the upper ridges, and also southwards into the Fjords; and he proceeded north to meet Eirik with his men."