What struck me about the cities of the West African forest is the archaeological evidence of their religious sacrifices. First, there were sacrifices of wild, not domesticated, animals (animal type unspecified). I’m more familiar with European sacrificial traditions where domesticated animals like oxen are sacrificed.What kind of wild animals might be sacrificed in a D&D forest culture? Deer? What would it mean about a religion if they were to sacrifice a stag? Somehow it makes me think of a religion that reveres the stag, but sacrifices it as part of a spring/fertility ritual. That might tie in with Robert Graves-type sacrificial-king human sacrifice.
Human sacrifice was practiced in some West African forest civilizations:
At least some [ceremonies] involved human sacrifices in which the victim or victims were asked to carry a message to the gods.
Human sacrifice is usually regarded in adventure fiction as the evil superstition of a barbaric people, a plot device to be thwarted by the hero. But in a D&D world, the beliefs leading to human sacrifice may well be right. Imagine if you can enlist help from your god by sacrificing a persuasive messenger. Or, imagine that a winter lasts unusually long – nine months, or a year – and the PCs track its source to a “Stag King” who refused to let himself be sacrificed to summon spring.