▁lands ; ▁this ▁did ▁not ▁change ▁when ▁California ▁became ▁part ▁of ▁Mexico ▁in ▁ 1 8 2 1 , ▁despite ▁the ▁fact ▁that ▁the ▁new ▁government ▁sec ular ized ▁the ▁Spanish ▁miss ions ▁and ▁as ▁a ▁result ▁fre ed ▁many ▁ens la ved ▁ind igen ous ▁people . ▁Additionally , ▁from ▁ 1 8 2 0 , ▁El ▁Cam ino ▁Vie jo ▁a ▁route ▁between ▁Los ▁Angeles ▁and ▁San ▁Francisco ▁Bay ▁along ▁the ▁west ▁side ▁the ▁San ▁Jo aqu in ▁Valley ▁began , ▁which ▁brought ▁settlement s ▁into ▁the ▁valley . ▁ ▁During ▁Mexican ▁rule , ▁the ▁mission ▁lands ▁in ▁the ▁San ▁Jo aqu in ▁Valley ▁were ▁sub div ided ▁to ▁wealth y ▁land own ers ▁( ranch eros ) ▁and ▁caused ▁even ▁more ▁conflicts ▁between ▁the ▁Mex icans ▁and ▁the ▁Native ▁Americans . ▁A ▁famous ▁leader ▁of ▁the ▁n atives ▁was ▁the ▁Y ok ut ▁Est an is la o , ▁who ▁led ▁revol ts ▁against ▁the ▁Mex icans ▁in ▁the ▁late ▁ 1 8 2 0 s ▁until ▁finally ▁defeated ▁in ▁ 1 8 2 9 ▁on ▁the ▁Stanis laus ▁River , ▁which ▁be ars ▁his ▁name ▁today . ▁ ▁Early ▁American ▁era ▁The ▁first ▁American ▁known ▁to ▁see ▁the ▁San ▁Jo aqu in ▁River ▁was ▁likely ▁Jed edia h ▁Smith , ▁a ▁ren owned ▁mountain ▁man , ▁fur ▁tra pper ▁and ▁expl orer . ▁In ▁ 1 8 2 6 , ▁Smith ▁arrived ▁in ▁Mission ▁San ▁Gabriel ▁Arc á ng el , ▁California , ▁when ▁the ▁region ▁was ▁under ▁control