in Kim Stanley Robinson's book, The Years of Rice and Salt, there's an alternative history discovering of America by the Chinese. When the Chinese encounter the Miwok, the first group of natives they meet, they conclude that the Miwok Don't farm because they don't need to as northern California (I assume that's where they are but it's hard tell) is so rich with game.
is that all accurate?
Pretty much. In fact, California in general had a rather high population density in pre-Columbian times. Game was indeed plentiful, and so was plant-based food (which is a given considering the abundance of animals). The Yokuts, the Miwok's neighbors to the south, had an average of 70,000 people throughout their territory.
While Native Californians (aside from the Mohave) never developed full-on agriculture, they still had a practice of land management. Tribes would burn stretches of land to clear old growth, rejuvenate the soil, and encourage the growth of perennials, transforming shrubland or forested areas into active fertile plains for the nourishment of both game and people.