Because southern Sweden had milder winters and earlier agriculture. It is mostly about the environment and the lifestyle, not about excessive migration.<quoted text>
So why does Sweden & Norway have more R1a haplogroup like Poland & less N haplogroup like the Baltic region & Finland?
No, it isn't.<quoted text>
There is a direct connection between Poland & Sweden by Cordedware culture.
It was largely likely similar to what happened on the eastern shore of the Baltic Sea - culture mediated by maritime mesolithic/neolithic hunter-gatherers.
The Swedish peculiarity is the mingling of mediterraneans with baltic (here baltic = Baltic Sea) hunter-gatherers into one agriculturalist group of people.
Do you suggest germanic languages from Poland to Sweden, sidestepping Denmark? I don't think so.<quoted text>
R1a haplogroup, Indo-European languages & Nordic phenotype went from Poland into Sweden in the Cordedware culture.
The "arrival" of the nordic phenotype?<quoted text>
Sweden was a part of Kurgan culture.
Earliest Kurgan found in Poland 6,000 years ago with other of the earliest Kurgan's found in Ukraine & Russia 6,000 years ago.
A Kurgan is found in Sweden 4,000 years ago about the time of the arrival of the Nordic phenotype & Cordedware culture in Sweden.
It was the agriculture that arrived, or more exactly, was taken over. Lifestyle morphs people.
PS. The nordic phenotype is mostly maritime, thus it has always been less agricultural (or rather, it has always been a more balanced diet).