▁Aut umn ▁period ▁( 7 2 2 – 4 8 1 ▁BC ), ▁two ▁revolution ary ▁improvements ▁in ▁far ming ▁technology ▁took ▁place . ▁One ▁was ▁the ▁use ▁of ▁cast ▁iron ▁tools ▁and ▁be asts ▁of ▁bur den ▁to ▁pull ▁p low s , ▁and ▁the ▁other ▁was ▁the ▁large - scale ▁har ness ing ▁of ▁rivers ▁and ▁development ▁of ▁water ▁conservation ▁projects . ▁Sun sh u ▁A o ▁of ▁the ▁ 6 th ▁century ▁BC ▁and ▁X imen ▁Ba o ▁of ▁the ▁ 5 th ▁century ▁BC ▁are ▁two ▁of ▁the ▁earliest ▁hyd ra ul ic ▁engine ers ▁from ▁China , ▁and ▁their ▁works ▁were ▁focused ▁upon ▁impro ving ▁ir rig ation ▁systems . ▁These ▁develop ments ▁were ▁widely ▁spread ▁during ▁the ▁en su ing ▁W arring ▁States ▁period ▁( 4 0 3 – 2 2 1 ▁BC ), ▁cul min ating ▁in ▁the ▁enorm ous ▁Du ▁Ji ang ▁Yan ▁Ir rig ation ▁System ▁engine ered ▁by ▁Li ▁B ing ▁by ▁ 2 5 6 ▁BC ▁for ▁the ▁State ▁of ▁Q in ▁in ▁ancient ▁S ich uan . ▁During ▁the ▁Eastern ▁Jin ▁( 3 1 7 – 4 2 0 ) ▁and ▁the ▁Northern ▁and ▁Southern ▁D ynast ies ▁( 4 2 0 – 5 8 9 ), ▁land - use ▁became ▁more ▁int ensive ▁and ▁efficient , ▁rice ▁was ▁grown ▁twice ▁a ▁year ▁and ▁cattle ▁began ▁to ▁be ▁used ▁for ▁p low ing ▁and ▁fert il ization . ▁ ▁In ▁circa ▁ 7 5 0 , ▁ 7 5 % ▁of