We read about various stories like Hansel and Gretel about witches that wanted to eat children. Were such stories like this pure fiction or was there a basis of truth of those?
If there was an andrenochrome appetite 150 years ago among the elites, like there is today, slavery would have been the simplest source to set up a steady supply of blood to these vampires. Just grab say you've sold a dozen slaves or their children to an unknown buyer from another state. Who was really keeping track?
It seems much of the opposition to ending slavery came from powerful individuals in Europe who shouldn't have had any any horse in that race.
Just putting that out there.
There was a certain point were slavery was forbidden amongst fellow Christians the start of serfdom and to get around that the Christian kingdoms started enslaving nomads from the north east who took the name Slavs. The Muslims did the same as they were not permitted to enslave fellow Muslims. Supposedly the fortunes made from that Slav trade heavily financed such rulers as the Hapsburg dynasty and is the reason of so much wealth there.