Kivutkalns153, Latvia, Bronze Age, 800–545 BC, R1a1a1b1a3-YP1370 (a subclade of R1a-Z284).
I guess this Z284 from Bronze Age Latvia proves that some R1a came to Scandinavia from East Baltic area.
These are the oldest R1a samples from Scandinavia:
Sweden RISE94, Viby, Götaland, 2621-2472 BC
Denmark RISE61, Kyndeløse, Zealand, 2650-2300 BC
Sweden LNBA, Ölsund, Hälsingland, 2573-2140 BC
Denmark RISE42, Marbjerg, Zealand, 2191-1972 BC
As you can see 3 of them are from Southern Scandinavia, but one (Olsund) is from Northern Sweden.
Olsund individual is discussed in this paper:
https://www.biorxiv.org/content/biorxiv/early/2017/03/03/113241.full.pdfhttps://www.biorxiv.org/content/biorxiv/suppl/2017/03/03/113241.DC1/113241-1.pdf
About the origins of Corded Ware culture:
http://eurogenes.blogspot.com/2017/12/corded-ware-as-offshoot-of-hungarian.html
R1a migrated to Scandinavia either from Latvia-Lithuania-Poland by boats across the Baltic Sea, or from Germany (both routes are possible). N1c migrated to Scandinavia much later and probably from Finland-Estonia (ultimately from North-Western Russia).
Possible routes of R1a migration to Scandinavia with Corded Ware culture (red arrows):
https://i.imgur.com/GfE3Abm.png
This paper claims that the Olsund sample was most autosomally most similar to Baltic Bronze Age samples:
https://www.biorxiv.org/content/biorxiv/early/2017/03/03/113241.full.pdf
CTRL + F type Olsund and find this info.
Also rock art of native Scandinavians (Non-R1) depicts the arrival of some R1-men by boats.
Native, Non-IE Scandinavians used to create rock carvings already ca. 6500 years ago.
They were documenting scenes from everyday life, such as hunting:
http://www.rockartscandinavia.com/frontpage.phphttp://fri.info.pl/rysunki-naskalne-alta/
At the beginning of the Metal Ages, completely new motifs appear in Scandinavian rock art. These new carvings depict the arrival - by sea - of large fleets of immigrants, who had the knowledge of metal-working, were armed in battle axes (see: Battle Axe culture) and worshipped foreign deities:
https://pl.wikipedia.org/wiki/Rysunki_naskalne_w_Tanum
Video:
https://www.youtube.com/watch?v=Ld6Dt-Lce6MVideo: https://www.youtube.com/watch?v=kDXQCUpjAyk
This artwork most likely depicts
an Indo-European high priest, an archetype of god
Thor:
^^^ This is consistent with Oslund R1a man being possibly descended from Baltic Bronze Age immigrants.