In the beginning, the first men came down from the sky. They were Thunderbird’s children. Thunderbird laid eggs on Saddle Mountain (in modern Oregon), and an giantess rolled five of those eggs down the mountain. Five men, each a different color, were born from those five eggs. So then they were in the valley.
When the men were in the valley, they found women there and pulled them out of the rocks. That was the beginning of the Chinook people.
(This is only one version of this story, and there are many others.)