An accurate assessment of aboriginal population in this area is impossible. The best we can do is try to make an intelligent guess. Several methods are available for this purpose--group comparisons, mission figures, area comparisons. Throughout the plains of the lower San Joaquin and Sacramento valleys the native social units appear to have resembled rather uniformly the political organization of the Yokuts in the central and southern San Joaquin Valley. There were aggregates, or communities, consisting of perhaps one, but usually more than one, village, and occupying a more or less clearly defined territory. These groups, as they may be called, can be identified by the plural names which are ordinarily attached to them--the Bolbones, the Leuchas, and so forth. Naturally these groups varied considerably in size, and concerning no single one of them can we be absolutely sure of the number of their people. Nevertheless, if we had data concerning enough of them, the variations due both to inherent difference and to inaccurate estimate would tend to cancel out and an approximate average could be secured. No pretence can be made that we have enough estimates to establish a mean which would be statistically satisfactory. Nevertheless, as so frequently happens when we are dealing with data of this character, we have to employ the information available to us or forsake the problem entirely. We have hitherto considered a number of the local groups mentioned above and have estimated their population as follows: Bolbones (restricted group, see p. 58), 1,500; Jusmites, 300; Tugites, 500; Nototemnes, 200; Leuchas, 900; Ochejamnes, 750; Guaypem, 300; Quenemsias, 400; Chucumes and Chuppumne, 1,500. The average for the nine groups is 705 or, in round numbers, 700. If we consider that the Aguastos, Chupunes, Ompines, Julpunes, and Tarquines were groups of the same character as the foregoing, then their total population may be taken as 3,500. The total baptisms shown in the mission books of the five northern missions (in fact, only San Francisco and San Jose) for these groups is 911. In previous instances we have estimated the aboriginal population by doubling the baptism number. This procedure is admittedly purely arbitrary and based upon the general consideration that, except for small local populations relatively close to the mission, it was impossible for the missionaries and soldiers to prevent the escape of a sizable fraction of the people. Of the five groups here discussed, the Aguastos, it is evident, were completely missionized or at least obliterated. A much greater proportion of the other tribes survived, as is attested by their probable migrations up the rivers. Hence for the entire population it is doubtful if even one-half received baptism. Using the value of one half, the aboriginal number would have been approximately 2,000.