Al Tabari was from a Christian family in the Abbasid Empire, near the Caspian Sea (modern Iran). His father, Sahl, was himself a doctor who proposed a new treatment for epilepsy. Al Tabari was born about 838 AD. When he grew up, he moved to Baghdad, where there were other scholars to talk to. There al Tabari converted to Islam, like many other people about this time.
Like the Roman doctor Dioscorides in the first century AD and like Chinese doctors in the 600s, and Mahdav in India in the 700s, Al Tabari wrote a big medical encyclopedia, or tafsir. He called his encyclopedia the Firdous al-Hikmat, the "Paradise of Wisdom". In his encyclopedia, al Tabari listed all the known treatments and medicines of his time. Al Tabari included not only Islamic, Greek and Roman medical ideas, but also medical research from India. He discussed the Greek idea of the four humors, and Neoplatonist ideas about how everything came from the One. But he also discussed the Indian idea of three humors - phlegm, air, and bile - and he mentioned the work of an Indian woman doctor who worked as a gynecologist.
Al Tabari followed Aristotle in believing (correctly) that light bounced off objects to reach your eyes. On the other hand, even though Egyptian doctors had known for a thousand years, al Tabari doesn't seem to have known the difference between arteries and veins.
Al Tabari also came up with new ideas of his own. He was the first doctor to include a lot of information about how to treat children. He also emphasized the connection between mind and body, saying that often when people felt physically sick, you could help them feel better by talking to them about their troubles.
Al Tabari's most famous student was al Razi, who continued his medical studies and became even more famous than his teacher. Al Tabari died about 870, when he was only about 32 years old.