Last two millennia of streamflow variability in the headwater catchment of the Yellow River basin reconstructed from tree rings

•A new annual (Nov-Oct) streamflow reconstruction of HCYRB at Tangnaihai Station of nearly two millennia was presented.•The nested principal component regression model is improved by the stepwise best tree-ring subset selection method in terms of AIC, CRSQ, VRSQ, CE, and RE.•The significant high-flow periods of HCYRB are the early 3rd century, circa 300 C.E., early 13th century, 16th century and circa 1900 C.E., while the low-flow periods are the late 5th century and late 15th century.•The reconstruction suggests that a warm climate is more likely accompanied by a high-flow period and low-flow periods are more likely to happen in cold periods.•The results provide adequate data foundation to analyze characteristics of streamflow of HCYRB and long-term optimal operation of Longyangxia over-year regulation reservoir.