Some knowledge of Medieval civilisation will help you understand Medieval medicine.
In the 5th century AD, waves of barbarians such as the Goths, Vandals, Saxons and Vikings invaded western Europe. Europe disintegrated into a huge number of small fiefdoms, each governed by a local lord, who protected his peasants - owned by him as 'serfs'. These tiny states could not afford universities for study, or public health systems.
Communications were difficult and dangerous, so ideas travelled slowly. During the Dark Ages, the monasteries alone managed to hang onto learning and knowledge, and even the ability to read and write. Many of the medical ideas of the Greeks and Romans were lost at this time, and survived only in the Muslim cities of the Middle East.
Similarly, technology was limited, and much of the advanced technical knowledge of the Romans was lost.
Medieval Europeans believed in the Christian God, so politics and everyday life, as well as medicine, were dominated by the Roman Catholic Church. Most peasants were extremely superstitious.
The key aspect of the Middle Ages was the emphasis on authority - people would believe what they were told against the evidence of their own eyes, and people who questioned authority risked execution.
After 1066, civilisation began to recover. Universities were established, eg in Paris in 1110, Oxford in 1167. Kings grew more powerful, and established courts as centres of culture and wealth. Trade and communications, especially, by sea, developed. Towns grew up, which created public health problems.
In 1258, Baghdad was destroyed by the Mongols, and much ancient knowledge that had been retained in the east but lost to the west was carried back to the west by fleeing scholars.
Causes of medical stagnation in the Middle Ages included:
The Church played a big part in medical stagnation in the Middle Ages. It discouraged progress by:
However, the Church did encourage people to go on Crusades, meaning that people travelled to the Middle East. Here they came into contact with Muslim doctors, who were significantly more skilled than their counterparts in Britain.