Complex sentence: The ruler replied that he would not stand and fight with Darius until they found the graves of their fathers and tried to destroy them-until then, they could continue their current technique as they had no cities or cultivated lands to lose.
Split into simpler sentences: The ruler replied that he would not stand and fight with Darius until they found the graves of their fathers and tried to destroy them. Until then, they would continue their strategy as they had no cities or cultivated lands to lose.