To avoid impacting the villagers at the foot of the mountain, the adeptus got his friend to chop his antlers off...
... he then kept on fighting until his blood was drained and his life ran out...
... And the blood that he lost in the battle turned into the Bishui River.
The Bishui River flows from northwest Liyue to Dihua Marsh, where it splits, flowing northeast to the lake that is southwest of Dawn Winery, east to the pool where Sal Terrae rests, southwest to Luhua Pool, and southeast into the Sea of Clouds.
People later used the Bishui River to transport goods across Liyue and still do so today.
The Bishui River is notable enough that adventurers can use it as a landmark and as a guide while adventuring.