A white line is the normal border between two regions.
A river between two white lines is also a common style of border between two regions, which acts as a normal border.
A thick black line represents a mountain border, which can never be crossed.
A colored line running along a border shows the border of a Nation.
When two Nations are neighbors, two colored lines run along each other, separated by the white border.
Sea areas are not regions and can never be crossed. Regions bordering the large sea area on the left side of the board are called coastal regions.
Larger letters in the name of a region show that the region includes a City or Stronghold.