Alright kiddo, there was a time long ago when there were two big groups of people living in Europe. One was called the Byzantine Empire and the other was the Bulgarian Empire. They didn't always get along and sometimes they would fight each other.
These times when they fought each other are called the Byzantine-Bulgarian wars. The wars lasted for a very long time, about 500 years! That's longer than you've been alive, right?
The Byzantine Empire was very powerful and had great armies. The Bulgarians were also strong and had warriors that were really good at fighting on horses. Sometimes, the Bulgarians would win the wars and sometimes the Byzantines would win.
At first, the wars were just about who had control over certain lands or cities. But then they got more serious and violent. The leaders of both empires really wanted to win and they didn't care how long it took or how many people got hurt.
The wars caused a lot of damage and sadness for the people living in those areas. Villages would get burned down and people would lose their homes. Many people died during those wars too.
But eventually, the wars ended and both empires were weakened. They were easier to conquer by other groups of people because they had lost a lot of their strength and resources during the wars.
So that's a brief explanation of the Byzantine-Bulgarian wars. It was a time of conflict and strife between two great empires, but it's all over now.