aders ▁introduced ▁ma ize , ▁domestic ated ▁animals , ▁war like ▁car v ings , ▁and ▁different ▁styles ▁of ▁cer am ics ▁and ▁architecture . ▁ ▁Import ance ▁ ▁The ▁oldest ▁radi oc ar bon ▁dates ▁( 3 6 0 0 ▁BC ) ▁of ▁Se chin ▁B ajo , ▁if ▁confirmed ▁by ▁additional ▁investig ations , ▁may ▁establish ▁it ▁as ▁oldest ▁site ▁of ▁monument al ▁construction ▁yet ▁found ▁in ▁the ▁Amer icas . ▁This ▁may ▁mean ▁that ▁Se chin ▁B ajo ▁in ▁the ▁Cas ma ▁and ▁Se chin ▁valle ys ▁may ▁claim ▁to ▁be ▁the ▁oldest ▁urban ▁site ▁in ▁the ▁Amer icas . ▁That ▁distinction ▁in ▁the ▁early ▁ 2 1 st ▁century ▁is ▁held ▁by ▁the ▁Norte ▁Ch ico ▁civil ization ▁of ▁which ▁the ▁oldest ▁ru ins ▁are ▁dated ▁at ▁about ▁ 3 5 0 0 ▁BC ▁at ▁Hu ar ic anga , ▁ ▁south ▁of ▁Se chin ▁B ajo . ▁Another ▁relevant ▁ancient ▁site ▁is ▁Band ur ria , ▁Peru ▁in ▁the ▁River ▁H ua ura ▁valley , ▁with ▁radio - car bon ▁dates ▁of ▁ 3 2 0 0 ▁BC . ▁ ▁Other ▁important ▁find ings ▁include ▁confirm ation ▁that ▁the ▁Cas ma ▁and ▁Se chin ▁valle ys ▁were ▁probably ▁occupied ▁c . 4 5 0 0 ▁BC ▁by ▁a ▁stable ▁and ▁sed ent ary ▁or ▁semi - sed ent ary ▁population ▁which ▁eventually ▁produced ▁the ▁monument al ▁architecture ▁found ▁at ▁Se chin ▁B ajo . ▁The ▁date ▁at ▁which ▁agricult ure ▁became ▁the ▁most ▁important ▁source ▁of ▁subs istence