Roman Empire (44 BCE - 476 CE)

The "Roman Empire" 

 is used to denote that part of the world under Roman rule from approximately 44 B.C.E. until 476 C.E. The term also distinguished imperial from Republican Rome. The expansion of Roman territory beyond the borders of the initial city-state of Rome started long before the state became an Empire. In its territorial peak after the conquest of Dacia by Trajan, the Roman Empire controlled approximately 5,900,000 km² (2,300,000 sq.mi.) of land surface, thereby being one of the largest ancient empires, exceeded only by the Persian Empire and by the Chinese Empire. At an early period, Rome adopted a republican structure with the Senate exercising power although all legislation had to be approved by an assembly of the people.