The official WoD sources say that a vampire requires between 50,000 and 100,000 people to support them, giving an upper limit of about 50,000 vampires in the entire world. I've always found this answer to be unsatisfactory, mostly because it implies that the number of vampires in the world was very small until modern times, as there were so few cities with enough population density to feed them. Indeed, this implies that most vampires would have been solitary for most of history. It's hard to see how the complex covenants and social relations of the Requiem could come about from a society with so few people.
Has anyone considered alternate calculations for vampire population density, and can you back them up? My motivation is a campaign I'm working on that I'd like to set in a city of roughly 150,000 people, but I want more than the 1-3 vampires that the standard numbers would provide.