No shit! Even in England, few people actually understand or really care about what happened between Romans and that (55 and 54BC and then finally: 43AD until about 410AD) and 1066 and the Norman invasion.
Something, something Saxons and Vikings and a round table and some burned cakes or something.
Its all rather sad, really because if you talk to a historian, that period is absolutely fascinating. Across the entire world, although we are here focusing on 400 until 1066 in England. Post 1066 it's all change ... of course it isn't - English would simply be French otherwise.
That period is (or was) nominally described as the Dark Ages because there was not much written evidence found and proper modern archaeology was not a thing until recently.
If you fancy a decent read then "The King in the North" by Max Adams puts things into perspective. By the way, I also think King Oswald was the real geezer. A couple of famous Hollywood actors now own a Wrexam (Wrecsam) footie club off of Wales. Just up the road is Oswestry. That's: Oswald's Tree.