Complex sentence: Journeying up the Missouri River, Lewis and Clark met Sacagawea, a woman of the Lemhi Shoshone tribe, who had been captured by another tribe and sold as a slave to Toussaint Charbonneau, a French-Canadian trapper, who made her one of his wives.
Split into simpler sentences: Journeying up the Missouri River, Lewis and Clark met Sacagawea, a woman of the Lemhi Shoshone tribe. Sacagawea had been captured by another tribe and sold as a slave to Toussaint Charbonneau, a French-Canadian trapper, who made her one of his wives.