Roman North Africa
By the 300s BC, the North African port of Carthage was actively engaged in policing the whole Mediterranean. Carthage made treaties, for instance, with the Etruscans in Italy, to protect the Etruscans from piracy from the Greeks in southern Italy. Carthage fought constant wars with the Greeks in Sicily over who would control which parts of Sicily.
But by the 200s BC, Carthage got into a war with the growing Roman Empire. In the first of the Punic Wars, the Romans succeeded in taking all of Sicily away from Carthage. In the second Punic War, which ended in 202 BC, the Romans got control of Spain as well, and really reduced Carthage to a very weak country. In the third Punic War, in 146 BC, the Romans destroyed Carthage altogether, and took over control of North Africa.
Roman amphitheater at El Djem, Tunisia
For a hundred years, Carthage was very weak. But under Julius Caesar about 50 BC, and then under later Roman Emperors, Carthage was refounded as a Roman city, and North Africa became an important part of the Roman Empire, exporting wheat and olive oil and pottery all over the western half of the Roman Empire. This trade continued even through the 400s AD, when the Vandals conquered North Africa and set up their own kingdom there.
Hannibal (First Book) by Robert Green (1997)
The Young Carthaginian by G. A. Henty (1860s, reprinted 2001) This is a good adventure story that can introduce kids to the wars between Rome and Carthage, but because it was written more than 100 years ago, it has some racist and unfair assumptions about the Romans being better people than the Carthaginians - watch out!
The Late Roman West and the Vandals by Frank M. Clover (not a kids' book) (1993)