The coast itself was very marshy, malarial and uninhabitable. Except for a few port cities, such as Bari, Otranto, Gallipoli and Taranto, all settlements are therefore located inland.
Given the description of the coastline as marshy, malarial, and uninhabitable, it is clear that most settlements are located inland due to these conditions, with a few exceptions like Bari, Otranto, Gallipoli, and Taranto being coastal cities.