Also notice the two different types of barracks. One for native troops, the other for foreign. In Carthage, the native barracks will provide you with all of your Punic/Libyan units while the foreign will give you access to Numidians and Maure. In Italy, you really won't get anything from native barracks but foreign ones will yield various Italian infantries, Greek units, and some Roman and Gallic units in the north. You will have to start relying on these more and more.