Phylogeography  is a young and fast-growing field that analyses the geographical distribution of genealogical lineages. It grew out of the new techniques of the 1980s that made it possible to determine DNA sequence variation from individuals across a species range, and hence to reconstruct gene genealogies. The spatial relationships of such genealogies may be displayed geographically and analysed to deduce the evolutionary history of populations, subspecies and species. In particular, the technical accessibility of mitochondrial (mt)DNA sequences in animal species kindled and fuelled this new field. Today, a range of DNA techniques, combined with new analytical methods and recent palaeoclimatic and geological studies are providing important insight into the distribution of genetic diversity around the globe, and how it evolved.