I don't know Crow. Poles are Northern people and Serbs are South, don't see much of a connection.
What was Europe in the past? We live in informative age, you have all on the net, did you bother to look?
Some 13.000-11.000 years ago 2 km thick ice in western, Central and Eastern Europe started to melt. Very slow process. At that time what was civilzation in Europe existed only on Balkan. Lepenski Vir culture (modern day Serbia, former Yugoslavia, Hungary, Romania, Bulgaria).
So what was Europe was Balkan. Now, take the map of the world and look how close is Balkan to Iran and India. See? When you look to Scandinavia, Balkan is practically center to Scandinavia and Iran/India.
Why I telling you this? To go out of the box. See, Ice age existed for many many thousends of years and Europe IE BALKAN population had to spread somwhere and that is why SANSKRIT was a Slavic language and that is why oldest Indian manuscripts and Rg Veda texts speaks of Srbinda (only European ethnic name mentioned ever by Rg Veda texts), being that was enemy to black Indra God. In short, with time and due to similar but still different reasons we got names such are Persia and Prusia. Name of Serbs goes with the name Ras. Its dualism under the scientific investigation. All in all many traces. Proved by science as small peaces of one bigger picture. From Balkan to Siberia and modern day Pakistan/India border existed oldest Sarmatian civilzation.
Now, when ice started to melt in Europe, the population from Balkan started to re-populate Europe. But not only from Balkan but from entire Sarmatian civlization.
Balkan-Baltic line was first backbone of civilzation in Europe. That is why name of Serbs in Europe survived solely there from Balkan Serbs, Molise Serbs, Lusatian Serbs, Kashubian Serbs. There was core and tradition was strongest. By all what I found on the net and sow, at the moment when Europe was entirely re-populated and Ice age completely gone that was maximum of old Sarmatian civlzation. In its farest extent Sarmats/Serbs covered entire Europe, Anatolia, Siberia, Kazahstan, etc, etc... Iran and Pakistan to Ind river and bordered with ancient Chinese. For the record, at that time 5.000 bc Black sea wasn`t sea but it was lake. Important fact for inteligent.
This my friend is European history. Only fraction of history of great Sarmatian civilzation.