Spinach comes from a central and southwestern Asian gene center where it may have originated from Spinacia tetranda, which is still gathered as a wild edible green in Anatolia. Spinach was unknown to the ancient Mediterranean world.
The diffusion of spinach into the Mediterranean was almost certainly the result of Arab ingenuity. Spinach, which does not grow well in hot weather, was successfully cultivated in the hot and arid Mediterranean climate by Arab agronomists through the use of sophisticated irrigation techniques probably as early as the eighth century A.D. The first references to spinach are from Sasanian Persia (about 226-640 A.D.) and we know that in 647 it was taken from Nepal to China where it was, and still is, known as the "Persian green." The first written evidence of spinach in the Mediterranean are in three tenth-century works, the medical work by al-Razi (known as Rhazes in the West) and in two agricultural treatises, one by Ibn Wahshiya and the other by Qustus al-Rumi. Spinach became a popular vegetable in the Arab Mediterranean and arrived in Spain by the latter part of the twelfth century where the great Arab agronomist Ibn al-'Awwam called it the "captain of leafy greens." Spinach was also the subject of a special treatise in the eleventh century by Ibn Hajjaj.
When spinach reached Provence it also became a popular vegetable, behind cabbage. Spinach is mentioned frequently as part of the fifteenth century Provençal ortolagia, the vegetable production of the garden. In the seventeenth century, the famous English philosopher John Locke reports having had a spinach and herb soup during his travels in southwestern France. In Anatolia, spinach was known by the thirteenth century, if not earlier, and served with meat and covered in garlic-yogurt sauce, a dish that was popular with the Seljuk Turks. The Italians were important for promoting the role this new vegetable played in the Mediterranean diet, as they favored spinach along with several other new vegetables both from the Old and New Worlds, in their gardens beginning in the thirteenth century. In Venice, cooks integrated Muslim flavoring techiques in dishes known as saur which were enriched with pine nuts and sultanas. Although fish, meatballs, and rice were so flavored, so were dishes of spinach.
The Arab influence in Spain is evident even today. Sometime ago a stylish dish in Cordoba was sajina, also called ásida, a kind of watery soup made with wheat flour cooked with spinach or other leafy vegetables. This soup seemed to be obligatory at family gatherings, holiday feasts, where you would also find stew/soups of lima beans or chickpeas. Sajina is a direct descendent of a popular stew from Islamic Spain.
Mediterranean Jews, the Sephardim, were also fond of spinach and prepare dishes such as shpongous, a savory baked dish of sheep's cheese and spinach that was customary as a dairy dish served on Shavuot, the holiday fifty days after Passover celebrating the Palestinian harvest and the anniversary of the giving of the Law.
In thirteenth century Damascus, burani was a popular dish of Persian origin, made with spinach or Swiss chard and yogurt, garlic, and spices. In 1614, Castelvetro calls for spinach to be used as the stuffing for tortelli.