To be fair, I think a lot of this lore isn't really laid out in the books in as interesting a way as they are here. Some of it is bits and pieces of casual dialogue across all the books pieced together by fans, and the bulk is from the linear history of Westeros as written in The World of Ice and Fire. If you're mainly interested in the backstory and lore stuff, you might want to grab that book instead. It's really nice.
Or read the Princess and the Queen, which is a novella published in the anthology Dangerous Women.
It's the story of the Dance of the Dragons, an early Targaryen civil war.
It is written as if it was a history written by a maester, and it's pretty great.