What were the names of the groups or individuals that played an important role in the exploration of the new western territories?

Key groups and individuals in the exploration of the western territories included the Lewis and Clark Expedition, led by Meriwether Lewis and William Clark, who mapped the land following the Louisiana Purchase. Other notable figures were John C. Frémont, who conducted several expeditions in the 1840s, and the Mountain Men, such as Jim Bridger and Kit Carson, who explored and settled the region. Additionally, various Native American tribes played crucial roles in guiding and assisting explorers through their territories.