Much of what is now considered Welsh to foreigners, i.e. Voice Choirs, and the traditional dress originated roughly in the 18th Century. The only problem is that Wales is so old! I'd honestly say that the Age of Saints is a good start point (Post Romans pre Normans) http://www.amazon.co.uk/A-History-Wales-John-Davies/dp/0140284753 this is a very good book! Also I'd recommend the BBC TV show 'The story of Wales' Hopes this helps!
> Shock, English colonialist who colonised the globe by force were going to give a shit about the adjacent nation they were forcing themselves upon
Wasn't a nation at the time. Wales was effectively formalised and unified by England.
> This is only evidence that Wales was taken under England's wing by force and that the lack of representation in the flag is a manifestation of the English attitude to Wales. "Shut up and be English".
Many of the Welsh were perfectly on board with being part of England at the time - many simply didn't care as life was rather different then.
> Aka, "Wales barely existed so grow up and move on".
Wales exists in it's current form thanks to the English. It's historical fact. This romantic idea that Wales was a nation under English or Roman or Saxon yoke is simply not true.
I'm dismissing you lot getting upset over a flag, and being so wrong.
There's some good information about how many of the Welsh were fully on board with unification here and here.
I would suggest reading those before posting again.