Complex sentence: The Kalevala is considered the national epic of Finland, it was compiled and edited by Elias Lönnrot while he was a district health officer in (then under the governance of Russia) eastern Finland.
Split into simpler sentences: The Kalevala is considered the national epic of Finland. It was compiled and edited by Elias Lönnrot while he was a district health officer in (then under the governance of Russia) eastern Finland.