Sherburne Friend Cook, The Aboriginal Population of the San Joaquin Valley…
“ The demography of the central valley is rendered still more complex by the fact that the contact with the white race took place in a series of steps rather than by a single overwhelming invasion. In central Mexico, or to a somewhat lesser degree in northwestern California, aboriginal life continued relatively untouched until there occurred a rapid and catastrophic occupation of the entire territory. As a result, the population was affected in a uniform manner throughout and a sufficiently clear line can be drawn between aboriginal and postcontact conditions. ”
