Fig 2. Temporal evolution of one realisation of the spreading process represented as a spreading tree.

Green nodes indicate the initially Romanised municipalities at 0 AD and blue nodes municipalities that have a Roman status in the respective time frame. Each connected component of the spreading tree is a tree rooted in a green node. These trees indicate how the municipalities got influenced. Roman roads network lines reproduced with permission from Ancient World Mapping Center [60] under a CC BY licence, original copyright 2015.