Arabic indigenous medicine developed from the conflict between the magic-based medicine of the Bedouins and the Arabic translations of the Hellenic and Ayurvedic medical traditions. Spanish medicine was influenced by the Arabs from 711 to 1492. Islamic physicians and Muslim botanists such as al-Dinawari and Ibn al-Baitar significantly expanded on the earlier knowledge of materia medica. The most famous Persian medical treatise was Avicenna's The Canon of Medicine, which was an early pharmacopoeia and introduced clinical trials. The Canon was translated into Latin in the 12th century and remained a medical authority in Europe until the 17th century. The Unani system of traditional medicine is also based on the Canon.