It is a sanctuary of the Barguzin valley, the master of wich is the spirit of stone. According to the legend, when Buryats moved the cattle to Chita region in winter, one bull refused to leave the valley, because he loved it much.
Three times people took him by force, but each time he came back, until he turned into stone and stayed in the valley forever. Since then people worship the stone and think that it protects all the inhabitants of the valley.
Buha-Shuluun - Bull-Stone. Sacred Places of Buryatia