Vampire off revenants—are common in vampire folklore. Garlic is a common example, a branch of wild rose and hawthorn plant are said to harm vampires, and in Europe, sprinkling mustard seeds on the roof of a house was said to keep them away. Other apotropaics include sacred items, for example a crucifix, rosary, or holy water. Vampires are said to be unable to walk on consecrated ground, such as that of churches or temples, or cross running water. Although not traditionally regarded as an apotropaic, mirrors have been used to ward off vampires when placed, facing outwards, on a door (in
Natural barrier Natural barrier A natural barrier refers to a physical feature that protects or hinders travel through or over. Mountains, swamps, deserts and ice fields are among the clearest examples of natural barriers. Rivers are a more ambiguous example, as they may obstruct large-scale movement across them (especially by armies) but may facilitate smaller-scale movement along them in boats, once some of the people in the region have developed the relevant technologies. Seas have likewise been an obstacle at first, then a convenient medium for transport along coastlines, and finally a medium for intercontinental transport. Natural barriers have been important factors