There used to be a great deal more "Sand Wars" between Karthage and the Ptolemaioi but the map was altered so that the two factions just barely touch. The team did not wish to completely separate the two and the result of the change prevented AI on AI wars most of the time. However, when you play one of the factions, the other will always attack you for the simple fact that the AI is programmed to hate you.

Usually, the AI will not completely defeat a faction that is at war with you, so the Seleukids will probably soon make peace with the Ptolemaioi so they can concentrate on fighting you.

Nobody has ever made a mod for EB that completely blocks off access through Libya.