Humans have cultivated garlic for at least 10,000 years. It has been theorized that it originated in southcentral Asia and northwestern China. Some anthropologists speculate that it was most likely the very first plant product intentionally cultivated by mankind. Sanskrit writings dating back 5,000 years refer to garlic as the “slayer of monsters,” because its odor warded off evil creatures. The ancient Egyptians said it could increase a person’s physical strength. In Transylvanian lore, placing garlic and a silver knife under one’s bed would keep vampires away.

It has been speculated that vampires, generally speaking, have two universal consistencies: they will always prey upon what their specific cultural
people consider most valuable and they will always be repelled by an inexpensive and common item. Considering how widespread and accessible garlic has always been, it is small wonder that vampires from all over the world and from every time period have been thwarted by this remarkable herb.

Source: Barbe, Vampires, Burial, and Death, 48, 63, 100, 131-132, 157-158; McNally, In Search of Dracula, 120-122; South, Mythical and Fabulous Creatures, 243, 246, 277; Summers, Vampire: His Kith and Kin, 187-188