I favor getting horses with our 5th city now and settling on the coast with our 6th city. It looks to me like we will likely need a sea (not coastal) going vessel to find trading partners not on our land mass. We need to learn Navigation to build sea going vessels. Navigation is in the next era. Also, we currently have available a food rich site for horses, verse the other sites which do not have as much food. Further, looking at the small map of the world, I would prefer to see us build a coastal city northwest of our territory by the 2 hills and 2 fishes which would put our harbor closer to the center of the map.