Bulgaria is at the northern edge of the Aegean Sea, between modern Greece and Turkey. This land was part of the Roman Empire. The Romans called this area Thrace, and the people who lived there were Thracians. In the 300s AD, they became Christians, like people in other parts of the Roman Empire. Like people to their north, most Thracians became Arian Christians.
When did the Bulgars arrive?
All through the early Middle Ages, groups of Slavs invaded Thrace from the north, and the Roman Emperors tried to fight them off. But in the late 600s AD, a different group of people invaded. These were the Bulgars. They were Turkic speakers from further east, in what is now Ukraine. Neither the Slavs nor the Roman emperor, Constantine IV, could fight them off.
The Bulgars’ leader, Khan Asparukh, took control of the area and started his own country, Bulgaria. There weren’t that many Bulgars, but they ruled the country. Their Slav and Thracian subjects had to put up with it.
To show that Bulgaria was a real country, their ruler Khan Krum published a law code about 800 AD. Krum also fought off a Roman invasion and killed the Roman emperor, Nicephorus.
Simeon the Great
Gradually the Slavs and the Bulgars married each other and became one people. The Bulgars stopped speaking their Turkic language and started to speak Slavic. In 864, under Boris I, the Bulgarians became Christians. But the rich people still pushed everybody else around and made them poor.
In the Roman Empire
About 1000 AD, the Bulgarians lost a lot of battles to the Russians, the Hungarians, and the Romans. They became part of the Roman Empire again, under Basil II. Basil, and later Roman Emperors, left the rich Bulgarians in power and left everybody else poor.
By 1185, the Romans had gotten weaker, and the Bulgarians fought for their independence. For a while, they were an independent country again. Their rulers married the rulers of the Roman (Byzantine) empire. But the rich rulers still treated everyone else very badly. One of the poor people, a pig-keeper called Ivaylo, led a revolution against the rich rulers in 1277. He made himself emperor for a while. Ivaylo tried to fight off the Mongols, but soon the Mongols took over Bulgaria. They ended up killing Ivaylo.
Bulgaria and the Ottoman Empire
Then in the 1300s, the Black Death killed a lot of people in Bulgaria. Bulgaria was so weak that it fell apart into several small countries that were always fighting each other.
So the Bulgarians could not defend themselves when the Ottomans invaded. In 1396, Bulgaria became part of the Ottoman Empire. Some people converted to Islam. The ones who stayed Christians had to pay heavy taxes to their new rulers.
Bibliography and further reading about medieval Bulgaria: