At one time, animal sacrifice was the most common form of public worship in the West.
So what happened to it?
We tend to think of Judaism as mother and Christianity as daughter, but in fact Christianity and Rabbinic Judaism are sister religions that arose at the same time in response to the self-same trauma: the destruction of the Jerusalem temple in 70 CE.
In ancient Hebrew religion, anyone could build an altar anywhere and offer up sacrifice there, but with the rise of the Jerusalem temple, a hard-fought process of centralization set in which eventually banned sacrifice anywhere else, on the logic of “one god, one temple.”
12th century England, the yeomanry crushed beneath the heel of their Norman overlords. Shooting a deer to feed your family is a capital offense. The people cry out to their ancestral god to free them.
And Herne, ancient god of the forest, hears his people's cry. He calls a dispossessed young English nobleman, Robin of Loxley, to be his son and to lead his people in their struggle against Norman oppression.
This is the heady premise of Richard Carpenter's landmark Robin of Sherwood, which aired in the UK from 1983 to 1985, the first television series to be shaped by the newly-emergent paganisms of the West. In the process, it transformed forever both the Robin Hood mythos and modern paganism itself.