In the Eastern Plains, various vampires have taken up an odd existence. Rather than dwelling in private and hunting at night, they live as lords of their domains, feeding gently off their serfs, and protecting the civilians from marauders. These lands are seldom large, as the vampire lord needs to be able to travel to the ends of his domain and back in one night. The serfs are most often goblins or kobolds as these weaker races are typically more desperate for protection, but human and halfling villages have been known to have noble vampires as well.
For the serfs, it is a peaceful existence. Their lords do tax them, but the taxes are less than what they would normally pay. For those who serve in the manor house, they are fed on, but they get to live in a luxurious mansion instead of toiling in the fields. For the vampire, he has a constant source of food, is defending during the day by archers (and frequently pets), and most often the threat of his vengeance is enough to keep enemies and looters away. It seems the perfect symbiotic relationship.
As for the neighbors, well, no one likes living next to an undead lord, but as long as they remain peaceful, the vampire and his serfs will typically remain within their own borders. For any thinking to overwhelm the vampire with numbers, few are willing to venture into his territory knowing that some of them are bound to be drained of their blood at night. Even taking his manor house, is not proof of safety, and who wants to risk being one of the ones killed during the night?