The Berber and Arab conquest of the Iberian Peninsula in 711 C.E. led to a profound transformation of the agricultural landscape. This was largely linked to the creation of irrigation systems and was particularly important in the eastern Iberian Peninsula, the Balearic Islands, and eastern Andalusia. The ecological conditions were favourable for the development of both small rural irrigated areas and huertas—large, irrigated areas usually associated with urban centres.

Much of the research conducted on irrigated areas in Andalusia is owed to the work of several pioneering authors; Thomas Glick’s research on the huerta of Valencia brought to light the existence of management techniques not directed by the state but rather local communities [1]. Pierre Guichard and André Bazzana [2] identified a link between Andalusi rural hydraulics and the settlement of Berber and Arab tribes in šarq al-Andalus (eastern Iberian Peninsula). Their proposal was based on the studies of Pierre Guichard [3], who identified the migration of Arab and Berber groups to the Iberian Peninsula and described the tribal organization of the Andalusi society. Miquel Barceló’s identification of rural peasant hydraulics challenged both the association of the new agriculture with the state and the supposed Roman origin of the huertas of the eastern Iberian Peninsula [4,5].

The initial attempts to study Andalusi hydraulics and irrigation were soon deeply influenced by Andrew M. Watson [6,7]. For Watson, the introduction of new plants of tropical origin into the Mediterranean agricultural cycle through irrigation made it possible to achieve greater crop diversification. This diversification and intensification brought greater and more substantial benefits to the area, which, in turn, led to population growth and urbanisation. Finally, the existence of a strong, centralised state would lead to the creation of a culturally homogeneous world—that of Dar-al-Islam—which would become the medium for the circulation of ideas, products, plants, and agricultural techniques. The role of elites as agents of diffusion would have therefore been essential. However, this view relies on the information provided by written documentation, which, in turn, is heavily biased by the perspective of the state. According to A. Watson, it was the combination of these processes that produced an agricultural revolution. This revolution cannot be understood as an abrupt change, but as a complex process that would gradually shape a “new agriculture” integrated into a “new network of exchanges” that would no longer resemble pre-Islamic agriculture.

Regarding new vegetables, our evidence is again based almost exclusively on the written record, such as the agricultural treaties, several references in historical or geographical Andalusi writings, and documents from the period immediately following the Christian conquest. In addition to the research carried out by A. Watson, it is worth noting the research done by other authors is also based mainly on Andalusi agronomic treatises [8,9,10]. See also the detailed compilation of species mentioned in agronomic works [11,12]. Regarding the information that can be obtained from the documentation generated after the feudal conquests, see [13,14]. This limitation makes it difficult to trace the actual spread of different plants, the local circumstances, and their chronology. Although Watson has been criticised, and some of the eighteen plants he studied may have been known and cultivated before the Islamic expansion (at least in the Middle East) [15,16], archaeology has not yet explored this question in sufficient depth [17]. Bioarchaeological techniques have been occasionally applied to Andalusi sites [18]. Successful results in this field depend on good preservation conditions. Therefore, the botanical macro-remains usually obtained by flotation or the sieving of sediments are not necessarily representative of the entire set of crops cultivated, but rather only of those that have been well-preserved by carbonization, mineralization, or exceptionally in waterlogged conditions. Under these conditions, the remains that are best preserved are those of cereals, legumes, and some stone fruits [19]. Although these findings are not representative of the plant diffusion from the 8th century onwards, some trends are being identified. At least two new species, pearl millet and rice, have been identified. Rice was among the crops mentioned by Watson [7], but pearl millet is a completely new find, especially well-spread and with textual references in the east of the Peninsula. Among fruits, apricots, quince, medlar, and citrus appear for the first time in Islamic sites [19].

The relationship established by Watson between population growth, the development of cities, commercial exchanges, and the state agency, on the one hand, and the diffusion of plants and hydraulic techniques of oriental origin, on the other hand, has been widely accepted, at least in the historiography of Al-Andalus. Various authors link the creation of urban irrigated areas (huertas) and the diffusion of techniques and plants with the consolidation of the Caliphate of Córdoba in the 10th century and the growth of the cities [20,21]. So, a long transitional period was characterised by the so-called “Islamisation” process [22,23,24] that had to be completed before the typical features of an Islamic society could be recognised and, according to these authors, state, religion, and urban development were the main drivers of the transformation of the agrarian landscape. Recently, Pedro Jiménez-Castillo and Inmaculada Camarero [25] have suggested that the emergence of geoponic books in the 11th century is closely related to the proliferation of private landowners in the growing cities of Al-Andalus. These landowners would have developed commercial agriculture.

On the other hand, other authors, following the approach of Miquel Barceló, have carried out extensive research on cultivation areas linked to networks of peasant settlements [26,27,28,29,30,31,32,33] and, more recently, on urban irrigated areas [34,35,36,37,38], which have demonstrated the capacity of immigrant peasant groups to create and manage a new agricultural landscape (Figure 1 and Figure 2). Fèlix Retamero [39] warned that the codification of techniques in agronomic treatises presents a biased view of technical and plant-based dissemination conducted by state and urban environments. He instead proposes that the success of the transfer of plants and techniques, especially irrigation, required a network of peasant settlements, where the conditions for the transmission of the agricultural technical package were developed.