An empire is an aggregate of many separate states or territories under a supreme ruler or oligarchy. This is in contrast to a federation, which is an extensive state voluntarily composed of autonomous states and

 ...

Empires originated as different types of states, although they commonly began as powerful monarchies. Ideas about empires have changed over time, ranging from public approval to

 ...

Bronze and Iron Age empires
Stephen Howe writes that with the exception of the Roman, Chinese and "perhaps ancient Egyptian

 ...

Roman Empire
The fall of the western half of the Roman Empireis seen as one of the most pivotal points in all of human

 ...

The chart below shows a timeline of polities that have been called empires. Dynastic changes are marked with a white line.
• The Roman Empire's timeline listed below includes the Western and Eastern portion.
• The Empires of

 ...

The Seven Stages of Empire
The military historian Sir John Bagot Glubbstudied eleven empires starting with the Assyrians in 859 B.C. and ending with the British in 1950 A.D. Sir John determined that each followed a remarkably similar pattern from birth to

 ...

Contemporaneously, the concept of empire is politically valid, yet is not always used in the traditional sense. For example, Japanis considered the world's sole remaining empire because of the continued presence of the Japanese Emperor in national

 ...