The Romans were a highly militarized society and their empire was built largely through military conquest. From the early days of the republic, the Romans expanded their territory by fighting and defeating neighboring peoples. They conquered much of Italy by the 3rd century BC, and went on to conquer Greece, Macedonia, and Hispania. In the 2nd century BC, the Romans began to expand into North Africa and the Middle East, and by the 1st century AD, they had conquered vast parts of Europe, Asia Minor, and North Africa.
Diplomacy
In addition to conquest, the Romans also expanded their empire through diplomacy. They often made alliances with local leaders and incorporated their territories into the empire. They also used diplomacy to settle disputes and to secure access to resources. For example, the Romans made an alliance with the Jewish kingdom in the 2nd century BC, and they negotiated with the Parthian Empire to secure access to trade routes.
Trade
The Romans also expanded their empire through trade. They established trade networks throughout the Mediterranean Sea and beyond, and they exported their goods to all parts of the empire. Trade helped to promote economic growth and to spread Roman culture and influence.
Assimilation
The Romans were very successful at assimilating the conquered peoples into their own culture. They encouraged the adoption of Roman language, laws, and customs, and they often granted citizenship to conquered peoples. This helped to create a sense of unity within the empire and to make the Romans more effective administrators.
Infrastructure
The Romans were also very good at building infrastructure, which helped to facilitate trade and administration throughout the empire. They built roads, bridges, aqueducts, and harbors. They also established a network of postal routes and developed a system of coinage that was used throughout the empire.
Military strength
The Roman army was one of the most powerful military forces in history. It was well-organized, well-trained, and well-equipped. The Romans also had a strong navy, which helped them to control the Mediterranean Sea.