Board Thread:General Discussion/@comment-5342139-20160428003224/@comment-7728766-20160512031042

Dreamer of daydreams wrote: I think RR should write more stories about the Norse and Egyptian pantheons. He wrote two 5 book series about the Greeks, 3 if you count the Trials of Apollo. He wrote 3 book series for the other ones. He can write more stories for MC and Kanes. I doubt Riordan's is going to write more books about the Egyptian and Norse pantheons.

I think the reason why he put the Kane Chronicles as a trilogy was because there was only enough source material for three books. It's also the same for Magnus Chase. Like what Long Island Spartan said, most material about Norse mythology have been lost and the only information that is available about the Norse world was through the Poetic Edda and Prose Edda.