I suppose they are referring to the events of the LOTR trilogy, so “Before the King” might just the kings of Gondor or even Arnor.
And I was watching onering.net’s livestream and they mentioned the first two episodes will almost be like a prologue with flashbacks from the events of the first age.I’m not sure how correct that is or they even have the rights to show the first age of the Middle earth.
And on a side note, was just browsing youtube for the videos about this series, and there's a good bit of hate for this even going back more than a year. Amazing how one can hate something just based on non-tangible rumours. And you can guess what sorta hate I’m talking about, thinly veiled on saying how its “ not according to Tolkien”. And just out of curiosity, I browsed a few of their channels, and you can see the template of their videos and stuff they hate tend to match up. And yeah ofcourse “woke” this and “woke” that being the key word.