Scandinavian origins of Mieszko I

Since Vikings placed fundaments for state of Rus, some wondered if is that possible, that they were also founders of Polish state?

There are some arguments for that theory:

1. In first written document, Mieszko is called ,,Dagome'' which could be Norman name - as Dagon.
2. There are some Viking weapons found in Poland
3. There were Jomsborg?, Viking city nearby.
4. Some of polish noblemen had Runes in their coats of arms.

These are however, most historians think, very weak arguments.

• ad 1) In no other chronicle or document Mieszko is called Dagome. Quite contrary, he is described as Msko, Mesco, etc - both by Ibrahim ibn Jakub, who was describing Poland in that time, and by Germans. Dagome Iudex, what's more important, is a terribly mangled copy, or rather a summary of document. For example, to this day historians are arguing what does ,,Shinesghe'' mentioned in that document means. Copyists who made that summary even didn't know about whom is he writing. He could easily made more mistakes.
• ad 2) This is a proof that Vikings were mercenaries or invaders in Poland. What's more, that findings are really few. Especially compared to Russia or other countries.
• ad 3) Jomsborg?, as historians (at least Polish) agreed many years ago, is a myth. The only source about Jomsburg are Sagas from Island, from XIII century. More probably there was city of Slavic pirates at that place.
• ad 4) In fact, some (like Awdañcy) had signs which can be interpreted as runes, becaues there is slight resemblance between runes and that signs. However as well they could be something else, like ,,znaki wlasnosciowe'' (who can translate that into English? Property signs isn't exactly what that means). And even if some Polish Noblemen are of Viking origins, that is again only argument that Polish rulers may use some Viking mercenaries.

There are also strong arguments against that theory

1. Dynastic tradition straighforward says, that Piasts originated from local population. There is no mention in tradition about Vikings, contrary to dynastic tradition in Rus
2. There are no signs in archeological evidence about some rapid changes in making weapons or fortresses, quite contrary, there is constant evolution of making weapons and fortresses. Fortresses are made in way not resembling Viking.
3. There is strong evidency in archeological and written documentation that Polish state developed at its own.