Complex sentence: Using sign language, the Shawnee (Savannah) warned the Westo of an impending attack from other tribes, earning the goodwill of the Westo, who began to prepare for the attack.
Split into simpler sentences: Using sign language, the Shawnee (Savannah) warned the Westo of an impending attack from other tribes. They earned the goodwill of the Westo, who began to prepare for the attack.