Moesia was a place a long time ago where people lived. It was in a part of the world called Europe and it was next to a big river called the Danube. There were lots of important things in Moesia, like cities and castles and farms where people grew food. Sometimes, Moesia was part of one big country and sometimes it was divided into smaller parts. People lived in Moesia for a very long time, but today it is not a place anymore because the borders of countries have changed over time.