Goguryeo wall murals: They have found blondes and blue eye'd people in these wall murals.
Language: I think it's mostly an inluence of Bhuddism...Like Sanskrit adn all that.
Korean's with blue eyes: I actually have heard of these people They're thought to be the descendents of Dutch people who washed up on the shores of Korea..(Shipwrecked)
Gold: Some people think that there is a connection between Shilla and Scythian gold...I don't remember if Scythians are aryans though.
When did Aryans start to scatter?
probably when they learned how to domesticate horses and later invented Ships.