Simplify the following text for a Grade 9 native English-speaking person.
Original: Natives in Southwest Alaska are mainly Central Yupik in the Yukon-Kuskokwim Delta and Bristol Bay areas , Alutiiq on the eastern Alaska Peninsula and Kodiak Island , Aleut in the Aleutians , Pribilofs , and the western Alaska Peninsula , and a few Dena ` ina Athabaskans near the western shore of Cook Inlet .
Simplified: Natives in Southwest Alaska are descended from different tribes , the Yupik , the Alutiiq , the Aleut and the Dena ` ina Athabaskans .