The Arabs controlled a large portion of Spain for (how long exactly?) a relatively long period of time. During which they (as I am to understand) introduced new techniques of irrigation and agriculture (such as lemons for instance).
But what impact did the Arab invasions and conquest have in the long-term for the culture of Spain? Many Jews and North Africans entered the picture during these times. What cultural influence did they have? Can these impacts be observed in Spanish culture today?
Please note that I am not talking about Latin influences (for example, the Roman Empire).
In the past, especially in the Franco era, the “official version” of history tended to depict the Christian reconquest as a process of purification - the “foreign” Arab and Jewish elements were expelled and Spain was “redeemed” for Catholicism and Europe.
It’s only been in recent years that the public history of Spain has come to terms with the Arab/Berber and Jewish influence on Spain. But this is still a touchy issue because some Spaniards are wary of immigration from North Africa and a possible reemergence of Islam in their country.
Aside from the architectural legacy Violet mentioned, I would point to the language (not just “Spanish” but Portuguese as well). There are several hundred Spanish and Portuguese words that are derived from Arabic.
In The Romance Languages, edited by Martin Harris & Nigel Vincent, it is suggested that the number of Arabic words in Spanish is “approaching four thousand” (p. 119). This isn’t surprising considering the Arabs’ approximately 700 year rule in Spain.
As far as the language goes, there is also some Celtic and Germanic influence, and it is my understanding that anything that cannot be conclusively shown to be Celtic, Germanic, Latin, etc. is tentatively given an Iberian origin.