The　mid-Pleistocene　transition　(MPT)　is　widely　recognized　as　a　shift　in　paleoclimatic　periodicity　from　41-　to　100-kyr　cycles,　which　largely　reflects　integrated　changes　in　global　ice　volume,　sea　level,　and　ocean　temperature　from　the　marine　realm.　However,　much　less　is　known　about　monsoon-induced　terrestrial　vegetation　change　across　the　MPT.　Here,　on　the　basis　of　a　1.7-million-year　delta　C-13　record　of　loess　carbonates　from　the　Chinese　Loess　Plateau,　we　document　a　unique　MPT　reflecting　terrestrial　vegetation　changes　from　a　dominant　23-kyr　periodicity　before　1.2　Ma　to　combined　100,　41,　and　23-kyr　cycles　after　0.7　Ma,　very　different　from　the　conventional　MPT　characteristics.　Model　simulations　further　reveal　that　the　MPT　transition　likely　reflects　decreased　sensitivity　of　monsoonal　hydroclimate　to　insolation　forcing　as　the　Northern　Hemisphere　became　increasingly　glaciated　through　the　MPT.　Our　proxy-model　comparison　suggests　varied　responses　of　temperature　and　precipitation　to　astronomical　forcing　under　different　ice/CO2　boundary　conditions,　which　greatly　improves　our　understanding　of　monsoon　variability　and　dynamics　from　the　natural　past　to　the　anthropogenic　future.