A number of sheep breeding nations, including Phoenicia, Italy, and Spain, are believed to have played a part in the development of the Merino sheep. However, it is generally agreed upon that the Moors, who dominated Spain through the eighth to thirteenth centuries, were primarily responsible for selectively breeding the animals to such an extent that the wool they produced became superior to that of all other sheep. Indeed, the word Merino may be of Moorish origin, possibly evolving from their word for a judge that settled disagreements about flocks between shepherds.
Arvu Lambakasvatus rahvaste, sealhulgas Foiniikia, Itaalia ja Hispaania, Usutavasti on mänginud rolli arengu Meriinolammastest. Siiski on üldiselt kokku lepitud, et maurid, kes domineeris Hispaania läbi kaheksas, üheksas, 13. sajandil olid peamiselt vastutavad valikuliselt aretus loomade sellisel määral, et vill nad tootsid sai parem kui kõik teised lambad. Tõepoolest, sõna Merino võib olla mauride päritolu, võib-olla arenev oma sõna kohtunik, et lahendada erimeelsused umbes karjade vahel karjased.