Carl Larsson “Midvinterblot / Midwinter Sacrifice”, 1914-1915
The scene shows a pagan sacrifice outside a temple in Ancient Uppsala. The sacrificial victim is the mythical King Domalde. There is no basis in history for the incident, but in Snorri Sturluson’s mythology, the sacrifice was to appease the Gods and ask for their interception in a succession of crop failures.
Midwinter Sacrifice shows very clear Art Nouveau influences. The form is strictly linear and the colour scale intensive, with large, gilded sections. The relief-like composition shows the square in front of a pagan temple, the instant before the sacrifice. The king to be slaughtered has been dragged, unclothed, to a gilded sled before the High Priest. The executioner conceals his blade behind his back. The king is escorted by heavily armed warriors; women perform an ecstatic dance to the left and men blow into serpentine bronze wind instruments.
I respectfully disagree with the OP: there is indeed historical precedent for this type of incident.
Writing about a hundred years before Snorri Sturluson, Adam of Bremen asserted that human sacrifice was still being practiced at Uppsala in his day. We know that the Celts also practiced human sacrifice, and for similar reasons as those given for King Domalde. Ned Kelly, keeper of antiquities at the National Museum, said of the Irish Celts, “The king had great power but also great responsibility to ensure the prosperity of his people…He had to ensure the land was productive, so if the weather turned bad, or there was plague, cattle disease or losses in war, he was held personally responsible.“ (Source: X)
It appears to me that King Domalde in this painting had been regally seated in the gilded sled, which significantly had been dragged by men, not horses, to the place of sacrifice. An honor guard of warriors follows behind. The king, wearing golden adornments, proudly arises to fling aside his cloak, preparing to present himself to the priest. Some of the onlookers are visibly distraught at what is about to happen. The man with the knife is bowing, a sign of respect to the gods, to the king, or both.
Remember that Jesus wasn’t the only semi-historical person said to have willingly died to give new life to his people.