The Merino is one of the most historically relevant and economically influential breeds of sheep, much prized for its wool. The origins of the breed are the subject of debate, with alternatives of it originating in flocks transferred from Morocco as early as the 12th century, originating and being improved in Extremadura in southwestern Spain, in the 12th and 13th centuries or from the selective crossbreeding of Spanish ewes with imported rams at several different periods. It was instrumental in the economic development of 15th and 16th century Spain, which initially held a monopoly on the trade in its wool. Since the end of the 18th century, the breed was further refined in New Zealand and Australia, giving rise to the modern Merino.
Today, Merinos are still regarded as having some of the finest and softest wool of any sheep. Poll Merinos have no horns (or very small stubs, known as scurs), and horned Merino rams have long, spiral horns which grow close to the head.