▁gre et ed ▁with ▁a ▁sight ▁of ▁horror . ▁An ▁ep ide mic ▁of ▁small po x ▁and ▁mal aria ▁brought ▁un int ention ally ▁by ▁the ▁Europe ans ▁had ▁swe pt ▁down ▁the ▁San ▁Jo aqu in ▁River ▁cor rid or ▁during ▁the ▁summer ▁of ▁ 1 8 3 3 , ▁killing ▁in ▁a ▁single ▁stroke ▁between ▁ 5 0 ▁and ▁ 7 5 ▁percent ▁of ▁the ▁entire ▁native ▁population ▁in ▁the ▁valley . Ex pl oring ▁the ▁Great ▁R ivers ▁of ▁North ▁America , ▁p . ▁ 1 2 8 ▁The ▁out break ▁did ▁not ▁van ish ; ▁it ▁continued ▁year ▁after ▁year ▁with ▁dimin ishing ▁ac uten ess ▁until ▁about ▁ 5 0 , 0 0 0 – 6 0 , 0 0 0 ▁ind igen ous ▁people ▁lay ▁dead . ▁Explorer ▁Kit ▁Car son ▁noted ▁in ▁ 1 8 3 9 ▁that ▁"... ▁ch ol era ▁or ▁some ▁other ▁fear ful ▁sc our ge ▁broke ▁out ▁among ▁them ▁and ▁ra ged ▁with ▁such ▁fear ful ▁fatal ity ▁that ▁they ▁were ▁unable ▁either ▁to ▁b ury ▁or ▁burn ▁their ▁dead , ▁and ▁the ▁air ▁was ▁filled ▁with ▁the ▁st en ch ▁of ▁their ▁decay ing ▁bodies ." ▁ ▁During ▁the ▁time ▁Mexico ▁was ▁in ▁control ▁of ▁California , ▁the ▁San ▁Jo aqu in ▁River ▁region ▁was ▁only ▁sp ars ely ▁populated , ▁and ▁used ▁almost ▁exclus ively ▁for ▁cattle ▁ran ch ing . ▁However , ▁when ▁California ▁won ▁independence ▁from ▁Mexico ▁in ▁ 1 8 4 6 , ▁becoming ▁part