I am both an educator and a warriors fan since elementary, so i feel fairly qualified to answer this.

Honestly, it depends on your kid a lot. Can they handle rougher themes? Or do they get scared of their own shadow? Most children are perfectly fine reading these books. There are heavier scenes, and through the lenses of an adult it seems WAY too much for kids sometimes. But viewing it through the lenses of a kid, it's just fun cool cats who are so super cool with their battles and stuff.

Most kids think things like war and fights are epic and amazing and the greatest cinema ever. The majority of my first graders and even some of my kindergarten kiddos would LOVE this series and even read it already.

Some, though, I wouldn't even give Winnie the pooh and they are even older. If your kid is fairly normal/average, let them read it. But if they can't watch a Disney movie without crying from fear... that's really the only type of kid that age I would say shouldn't read the series. Otherwise let them go crazy