  We introduce a stochastic cellular automaton as a model for culture and
border formation. The model can be conceptualized as a game where the expansion
rate of cultures is quantified in terms of their area and perimeter in such a
way that approximately geometrically round cultures get a competitive
advantage. We first analyse the model with periodic boundary conditions, where
we study how the model can end up in a fixed state, i.e. freezes. Then we
implement the model on the European geography with mountains and rivers. We see
how the model reproduces some qualitative features of European culture
formation, namely that rivers and mountains are more frequently borders between
cultures, mountainous regions tend to have higher cultural diversity and the
central European plain has less clear cultural borders.
