What is property owned by individuals or companies, not by the government or the people, called?

Private property.

Explanation:

Private property is the name allocated to land that is owned by non-government entities, such as person or a company. It is distinguishable from property that is owned by the government and which it is called public property, like government buildings. Private property is a legal term that has a long history, in philosophy and political theories that go back as far as Ancient Greece. In colloquial terms it refers to land ownership.  

i would say it is the roman empire europe after the norman conquest.