Highly recommend "A Concise Histoy of Korea: From Antiquity to the Present" 2nd. ed. (2016) by Michael J. Seth. It's an undergraduate treatment of Korea's history until 2015, so it's a bit lengthy, but Korea's history is utterly fascinating, and the book is very engaging and well-written. I'd say you might be a little bored by the first chapter (prehistory), but even that was interesting enough to get me through and fall in love in the second and third chapters.

And yes, they recorded everything. The amount of recorded history Korea would have without the Mongols, the Japanese, and eventually the civil war would be staggering.