Geogen is the short form for "geographical genealogy" which means location based ancester research. On this website you can create maps which show the distribution of surnames in Germany. Significant concentrations can point to a local root of the family or of the family name.
The maps generated on this site are licensed under the Creative Common License Attribution- ShareAlike 4.0 International (CC BY-SA 4.0). You are free to: Share (copy and redistribute the material in any medium or format) and Adapt (remix, transform, and build upon the material for any purpose, even commercially). You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. If you remix, transform, or build upon the material, you must distribute your contributions under the same license as the original.