Even before the purchase, Jefferson was planning expeditions to explore and map the lands. He charged Lewis and Clark to "explore the Missouri River, and such principal stream of it, as, by its course and communication with the waters of the Pacific Ocean; whether the Columbia, Oregon, Colorado, or any other river may offer the most direct and practicable communication across the continent for commerce". Jefferson also instructed the expedition to study the region's native tribes (including their morals, language, and culture), weather, soil, rivers, commercial trading, and animal and plant life.