The important thing is the method, when we are talking about history, there is no space for campanilism or things pro-south or pro-north
however to give an answer to the open post, we can't say "the south was poor becouse was poor" to answer, is a tautology. however the south loss during centuries is prominency, like other parts of the world during human history, the correct way to answer is a neutral historical analysis.
Modern Age, Discovery of the atlantic routes, expansion of the Ottomans, in a context where Italy lost its centrality, becoming a noble periphery of Europe, the south suffer this condition more acutely, also due to historical situations dating back to the Norman conquest. The clientelism within a rigid feudal society, caused a weak development of the bourgeoisie. to worsen the situation, the Spanish domination , not only made the south only a periphery of an huge empire, but caused also a further legitimization of feudal relations and economic arrears. (In fact, problems due to feudal arrears and bad economic doctrines, appeared also in Spain). The aftermath of this continued de facto also in the contemporary age, and of course also had its effect on the history of our country post-unification.
So in game terms:
Naples deserve prestige, as center of prestige and royal power, vivid enough to be a center of the renaissance, connected enough to not be totally foreign to the Enlightenment (also spain invested on this directly, and indirectly also with the kingdom of sicily post 1734)
the rest of southern Italy while being economically inserted into a wide-ranging agricultural circuit, was penalized by the fossilized remain of this "feudal" view of the economy, with all the consequences about the society (consequences appeared, with the obvious differences, in all the areas that suffered a static feudal economy), that ignored his large potential about the industrial plants, to continue with an ill-planned economy.
The consequences of this evolution, reflected on every other sector, a spontaneus middle class remained an exception and the intellectual bearer of foreign or original ideas was without audience.
Every economic activity, concerning fishing, agriculture, mining, etc.. or was under foreign influences little interested in the development of the area, or was influenced by centuries of political, economical and social stagnation.
so, like other part of world, the historical context and the contingent policies, can justify a not central economic position of southern italy during the EUIV timeframe.
