There was no one ruler. It was a 1000 years long, so many people ruled many countries at different times.
the centimetre ruler
There was no first ruler in the Middle Ages. Historians debate over when the Middle Ages started, and the dates I have seen range from 395 to 500. We can be pretty sure that through all that time there was more than one ruler at any one time in the different countries in Europe.
Thomas Aquinas
The period of time from 500 AD to 1500 AD is called the Middle Ages.
Rulers usually inherited their titles. Sometimes, as in the case of Richard III, they took the titles by usurpation.
The knights' lord or ruler who employed them had power over them to use them such as a government would use its army.
There was no explorers in the middle ages. When exploration started that is when the middle ages ended.
One of the Catholic thinkers in the Middle Ages who wrote about the right to overthrow an unjust ruler was St. Thomas Aquinas. In his work "Summa Theologiae," Aquinas argued that if a ruler becomes a tyrant and abuses his power, the people have the right to resist and potentially overthrow him, as long as it is done for the common good and with the intention of restoring justice and order.
The third period of the Middle Ages was the Late Middle Ages. The first is called the Early Middle Ages or the Dark Age. The second period was the High Middle Ages.
Early Middle Ages 400 - 700, High Middle Ages 700 - 1300, Late Middle Ages 1300 -1500.
Middle ages
It was not worn in the Middle Ages.