0 – 3 0 0 0 ▁BC . ▁There ▁is ▁arch ae ological ▁evidence ▁that ▁un hus ked ▁rice ▁was ▁stored ▁for ▁the ▁military ▁and ▁for ▁bur ial ▁with ▁the ▁dece ased ▁from ▁the ▁Ne ol ith ic ▁period ▁to ▁the ▁Han ▁D ynast y ▁in ▁China . ▁ ▁By ▁the ▁late ▁Ne ol ith ic ▁( 3 5 0 0 ▁to ▁ 2 5 0 0 ▁BC ), ▁population ▁in ▁the ▁rice ▁cultiv ating ▁cent ers ▁had ▁increased ▁rapidly , ▁centered ▁around ▁the ▁Qu j ial ing - Sh ij ia he ▁culture ▁and ▁the ▁Li ang z hu ▁culture . ▁There ▁was ▁also ▁evidence ▁of ▁int ensive ▁rice ▁cultiv ation ▁in ▁p addy ▁fields ▁as ▁well ▁as ▁increasing ly ▁s oph istic ated ▁material ▁cult ures ▁in ▁these ▁two ▁regions . ▁The ▁number ▁of ▁settlement s ▁among ▁the ▁Yang t ze ▁cult ures ▁and ▁their ▁sizes ▁increased , ▁leading ▁some ▁ar che olog ists ▁to ▁character ize ▁them ▁as ▁true ▁states , ▁with ▁clearly ▁advanced ▁so cio - polit ical ▁structures . ▁However , ▁it ▁is ▁unknown ▁if ▁they ▁had ▁central ized ▁control . ▁ ▁Li ang z hu ▁and ▁Sh ij ia he ▁decl ined ▁ab rupt ly ▁in ▁the ▁terminal ▁Ne ol ith ic ▁( 2 5 0 0 ▁to ▁ 2 0 0 0 ▁BC ). ▁With ▁Sh ij ia he ▁shr inking ▁in ▁size , ▁and ▁Li ang z hu ▁disappear ing ▁altogether . ▁This ▁is ▁largely ▁believed ▁to ▁be ▁the ▁result ▁of ▁the ▁south ward ▁expansion