What did the Indians do before the founding of the California Missions?

The Indians began to live in what we now know as California 8 -10,000 years ago so I would say they survived pretty well.

Because of the mountains and desert barriers they were pretty isolated from other North American Indians although there was some trading that took place. The California Indians learned to live with and use the rich resources that were available to feed, shelter, clothe and entertain themselves. They lived off the bountiful land and ate what was available – fish, game, edible plants etc. Acorns were a plentiful source of good. Finding food was the responsibility of the entire tribe and took up much of their time.

The California Indians lived in villages – many as small as 50 people, a few large enough to be called towns. The villages / tribes traded with each other.

They played games, cleaned themselves in sweat houses and worshiped the Supreme Being that created the earth. Their god had various names, the "Above Person", the "Immortal One" the "Earth Maker."

In summary the Indians lived rich and full lives, surviving by living off the land (and respecting it) and raising families.