Short answers, pulled from the story.
The Roman Republic destroyed Carthage in 146 BC after the Third Punic War. Scipio Aemilianus led the final assault that turned the city into ash before Rome established its first African province on the scorched earth.
Julius Caesar created the second province called Africa nova during his civil war between 49 and 45 BC. He took land directly from the Numidians to expand Roman control while renaming the original territory Africa vetus.
Muslim forces captured Carthage in 698 AD ending all Roman presence permanently. Hassan ibn al-Nu'man al-Ghassani led Umayyad armies that defeated the Exarchate after decades of struggle to establish Islamic rule across Northwest Africa.
One million tons of cereals were produced annually in Northwest Africa alone according to contemporary estimates. This amount fed the Roman populace for eight months each year while Egypt supplied the remaining four months of grain needed for Rome's growing population.
Chemical analysis traces specific production centers to Sidi Marzouk Tounsi, Henchir el-Guellal and Henchir es-Srira in central Tunisia. These locations produced fine red-fired clays that traveled along established Mediterranean routes starting in the last third of the first century AD.