Cenozoic δ18O and δ13C records of pedogenic carbonate from northwestern China.
Drying of the Lanzhou Basin began at ∼33 Ma due to the retreat of the Tethys Sea.
Asian inland aridity was further enhanced at ∼22 and ∼3.5 Ma.
C4 plants expanded within the Lanzhou Basin after ∼3.5 Ma.