▁and ▁min ers ▁in ▁what ▁was ▁then ▁the ▁immense ▁county ▁of ▁Mar ip osa ▁in ▁California . ▁ ▁C aus es ▁of ▁the ▁War ▁The ▁Mar ip osa ▁War ▁was ▁spark ed ▁by ▁the ▁ 1 8 4 9 ▁California ▁Gold ▁R ush , ▁the ▁discovery ▁of ▁the ▁gold ▁for ged ▁a ▁California ▁Tra il ▁which ▁for ked ▁off ▁south ward ▁from ▁the ▁Oregon ▁Tra il . ▁Th ous ands ▁of ▁hope ful ▁gold ▁seek ers ▁crossed ▁this ▁trail ▁into ▁northern ▁California , ▁which ▁at ▁this ▁point ▁in ▁time ▁consisted ▁of ▁mostly ▁Native ▁Americans , ▁and ▁Cal if or ni os ▁( the ▁descend ants ▁of ▁early ▁Spanish ▁sett lers ). ▁By ▁the ▁end ▁of ▁May ▁ 1 8 4 9 , ▁it ▁is ▁estimated ▁that ▁ 4 0 , 0 0 0 + ▁had ▁entered ▁Native ▁American ▁territory . ▁This ▁added ▁divers ity , ▁with ▁the ▁land ▁now ▁containing ▁many ▁different ▁imm igr ants ▁from ▁Mexico , ▁South ▁America , ▁Europe , ▁Australia , ▁and ▁China . ▁ ▁This ▁international ▁mix ▁sw elled ▁California ' s ▁non - Native ▁American ▁population ▁from ▁some ▁ 1 4 , 0 0 0 ▁in ▁ 1 8 4 8 ▁to ▁ 2 0 0 , 0 0 0 ▁in ▁ 1 8 5 2 . ▁ ▁Out break ▁of ▁the ▁War ▁The ▁gold ▁r ush ▁increased ▁pressure ▁on ▁the ▁Native ▁Americans ▁of ▁California , ▁because ▁min ers ▁forced ▁Native ▁Americans ▁off ▁their ▁gold - rich ▁lands . ▁Many ▁were ▁pressed ▁into ▁service ▁in ▁the ▁mines