As a trading culture, the Arabs travellers had access to plants from China, India and other distant places. Muslim botanists and Muslim physicians significantly expended on the early knowledge of medical substances. For example, Al-Dinawari described more than 637 plant drugs in 9th century and Ibn Al-Baitar described more than 1400 plants, foods and drugs, over 300 of which were his own original discoveries.
The experimental scientific method was introduced in the field in the 13th century Andalusian botanist Abu Al-Abbas Al-NAbati teacher of Ibn Al-Baitar. He separated unverified reports from those supported by actual tests. This allowed the study of medical substances to evolve into science of pharmacology.