Before American colonizers began arriving in the 1800s, the land was inhabited for many centuries by two bands of indigenous Chinook peoplethe Multnomah and the Clackamas. The Chinook people occupying the land were first documented in 1805 by Meriwether Lewis and William Clark. Before its European settlement, the Portland Basin of the lower Columbia River and Willamette River valleys had been one of the most densely populated regions on the Pacific Coast.