Today, most of the pistachios consumed in Italy are imported from Iran and Iraq. That wasn't always the case. Throughout the middle Ages, the pistachios eaten by Sicilians came from eastern Sicily, where they are still grown, particularly around Mount Etna and in the Bronte area.

Traditionally cultivated in India, central Asia, the Middle East and the eastern Mediterranean, pistachios were introduced in Sicily in ancient times, probably by the Phoenicians, the Sisals or the earliest Greek colonizers. There is little doubt that the ninth-century Arab rulers of Sicily encouraged the wider cultivation of the tasty nuts.
It was probably the Saracen Arabs who began the practice of radically pruning pistachio trees every two years to increase nut production.

Pistachios found their way into many of the sweet confections still made today, created in Arab Sicily using cane sugar.

That's how most of Sicily's pistachio production is now used --either in pastries or in pistachio ice cream.
Sicilian pistachios are slightly longer and thinner than those grown in the Middle East. They also seem to have a stronger, sharper taste, due perhaps in part to the volcanic soil in which they're grown.
They are not exported in large quantities. Unlike olive growers, pistachio farmers receive little economic support from the Italian government. Here in Sicily, almonds seem to have been preferred to pistachios, probably because the cultivation of pistachios was historically more difficult.
Almond trees, which require somewhat less water, seem generally hardier than pistachio plants. Sicily is suffering an extended drought; in recent years, decreased annual precipitation has reduced the quantity, but not the quality, of Sicilian pistachios.

Pistachio Vera is the edible variety of pistachio grown in warm, dry climates around the world, even in California. The pistachio tree is an evergreen native to Asia, and the very word traces the fruit's origin. The English word pistachio comes to us from the Old Italian pistachio ("pistachio" in modern Italian), from the Greek pistachio, which in turn derives from an Old Persian word.

Pistachios are a good source of protein, fat, fiber, vitamin B6 and thiamine. The mature kernels are generally greenish with reddish areas, assuming a brownish color when toasted. However, it is possible to eat them dried rather than toasted.
Widely regarded as a snack food, pistachios are well-suited to Italian recipes, including some that call for pine nuts. Pistachios are excellent in rice dishes or as a garnish in main courses.

To prepare pistachios in this way, simply remove them from the shell, allowing the kernels to soak for at least an hour in cold water flavored with lemon juice. In this way, the tender pistachios will reveal their truest flavor.
A restaurant in Palermo serves tender Sicilian pistachios over gnocchi as part of a delicious gorgonzola (blue cheese) sauce.