"Diego Gambetta, however, presents an elegant economic theory of the Mafia's origins: mafiosi are private entrepreneurs whose function is to provide protection of individual property rights in a society in which the state fails to perform this basic service." -- Fukuyama, p. 114
In fact, according to what I have read, state law enforcement was almost entirely absent in Sicily when it was ruled by the Kingdom of the Two Sicilies in the 19th century. (One of the "Two Sicilies" was the mezzogiorno.)
As Gambetta writes:
"In all likelihood, by the time Italy was unified in 1860-61 the foundations of this peculiar industry were already firmly in place. Not only did the state have to fight to establish itself and its law as the legitimate authority and a credible guarantor in a region where no such authority had previously existed."
So, in Sicily before the creation of the Italian state, there was effectively no state at all. The Mafia filled this vacuum.
This history would seem to present a problem for anarcho-capitalists. Our good friend Bob Murphy "deals" with this problem by contending the problem was... the state!
So, although we are dealing with a region in which state control was almost entirely absent, which would seem to be ideal conditions for the establishment of ancap defense agencies, the mere whiff of the state in their vicinity caused these agencies to become violent criminal gangs. This does not argue well for the stability of anarcho-capitalism!