All numbers on the makeup of Peru's republican population are wrong, the one point on which historians can agree. Peruvian governments had neither the capacity nor the will to mount thorough surveys of their scattered and elusive Andean subjects. Between the late viceregal census of 1791 (reporting a population of 1,076,000) and the first modern effort of 1876 (yielding a count of 2,699,000) lies a century of demographic no man's land, despite partial surveys claimed for 1812, 1836, 1850, and 1862. Unfortunately, historians cannot fly back in time and redo the head counts missed or mismanaged by successive governments, although this miracle has seemingly been worked for the older Incan and conquest periods.1 The best scholars can attempt at this point is to untangle the confusions of existing census documents and bring new evidence to bear on their strengths and weaknesses.