I believe he is bay... I was told he was dark bay with dun highlights... his butt is definitely lighter and easier for sun fading... but I just wanted to make sure if I could tell the difference and learn from this thread :) Thank you.
He is actually a brown Sun fading is what would cause that colouration on a bay... except he is lighter in areas that would fade last. If his colour was caused by fading, you would expect the fading to start along the top of the horse - where the sun has the most contact if you will.
Oooh... I think I'm glad I second guessed and edited my post haha! I was always led to believe he was bay, and so I was thinking "Seoul must be bay too." I thought I had never owned a brown horse before... guess I've owned two now... thanks for clearing that up for me Chiilaa!!