Oregon's history goes back 15,000 years when Native American tribes like the Paiute and Tillamook lived there. In the 1500s the Europeans arrived in what is know Oregon. In 1803 Oregon was bought as part of the Louisiana purchase. In 1804 president Thomas Jefferson sent Lewis and William clark to map the newly purchased land that which included Oregon. Starting in the 1840s American settlers arrived by the Oregon Trail, a more than 2,000 mile long route for wagon trains. The Columbia Plateau is Oregon’s largest geographical region, and it fills almost the entire eastern half of the state. in 1859 Oregon became the 33rd state.