As a precursor of the bow, the friction stick is documented in medieval Chinese sources in connection with vaulted zithers and the spike fiddle hu ch'in that were subsequently to be bowed, except that in Wu-an County, Hopei, the vaulted zither ya cheng has retained its original name (elsewhere it is known as la ch'in) and is still bowed
with a sorghum stem dusted with resin, as Picken (1965) has ascertained.
We first hear of the bow's existence...