Three factors, human population density, topography, and culture interact to create temporal and spatial differences in the frequency of fire at the landscape level. These factors can be quantitatively related to fire frequency. The fire model can be used to reconstruct historic and to predict future frequency of fire in ecosystems, as well as to identify long-term changes in anthropogenic fire regimes. Topographic roughness is positively related by a regression equation to the length of mean fire intervals indicating that fires are less frequent in rough than in flat terrain during periods of low human population density. The strength and direction of this relationship diminishes as the frequency of anthropogenic ignitions increases to the point that the fuel environment is pyre-saturated. Human population density is a master variable in understanding anthropogenic fire regimes and topographic effects. The interactions of these factors through time creates at least two stages in anthropogenic fire regimes: an Ignition Limited Stage in which fire frequency is function of human population density, and a Fuel Limited Stage during which fire frequency is limited by fuel production and is independent of increases in human population density.