Previously I determined the terrain according to the biomes. The problem, in many places it’s not the reality. For example, in Egypt, especially the Nile Delta. On the Climate map, everything is a desert, but in reality, it’s all green around the Neil.
So I took the GlobCover Data, which gives a better representation of the terrain without changing the biome. This also gives a better transition between biomes and more variation of the ground.