On the other side of the continent, another civilization was also developing.
The late Roman Republic was an era of extreme turmoil.
The original Roman Republic inherited the ancient democratic tradition and continued to practice the republican system, but the turbulent times placed it in a precarious position.
Coupled with Caesar's authoritarian politics, this posed a significant internal threat to the Roman Republic.
Octavian, then serving in Apollonia, Greece, heard that he had been named Caesar's heir. He immediately marched back to Rome.
At this time, Rome was controlled by the republican senators Brutus and Cassius, who had murdered Caesar.
Octavian formed an alliance with Caesar's colleagues Mark Antony and Lepidus. Together, they purged the Senate of dissenters, leading to the deaths of over a hundred senators and thousands of knights.
Antony and Octavian led their armies in pursuit of Brutus and Cassius, who had fled to the East.
Later, Brutus and Cassius were defeated and committed suicide at the Battle of Philippi. Octavian returned to Rome, while Antony headed to Egypt, dividing Rome into eastern and western halves.
Octavian garnered popular support in Rome, consolidated his power, and simultaneously maligned Antony, accusing him of colluding with foreign powers and rebelling against Rome, leading to escalating tensions between them.
Finally, Octavian declared war on Antony. Antony and his allied forces from Egypt engaged Octavian at the Battle of Actium in Greece. Antony was disastrously defeated and fled back to Egypt.
Subsequently, Octavian invaded Egypt, leading to the downfall of the Ptolemaic dynasty and the incorporation of Egypt as a Roman province.
Octavian skillfully employed political maneuvers, publicly announcing the relinquishment of all powers to restore the republic, while at the same time feigning reluctance under the Senate's and citizens' pleas, accepting absolute power that completely contradicted republican principles.
Ultimately, Octavian, through his masterful tactics and de facto imperial authority, proclaimed the establishment of the Roman Empire.
The Roman Republic fell, and the Roman Empire was founded.
After Octavian's death, Augustus inherited the throne.
During Augustus' reign, he reformed the military, reduced its size, and established the empire's first standing legions and Praetorian Guard. He founded the "Imperial Treasury" to oversee fiscal matters, reorganized administrative divisions, and delineated senatorial provinces from imperial provinces to solidify the emperor's supreme military authority.
Augustus also used diplomacy to establish friendly relations with Parthia and Armenia, stabilizing the Roman Empire's external environment.
Subsequently, the internal affairs of the Roman Empire were stabilized by the emperors, internal consumption decreased, and development accelerated.
It took nearly ten years for the Roman Empire to conquer all of Spain.
Four years later, Augustus dispatched troops to the eastern Alps and the upper Danube, capturing large territories and establishing the provinces of Raetia and Noricum. He then campaigned along the middle and lower Danube, establishing the provinces of Pannonia and Moesia.
Through constant conquest, the Roman Empire acquired wealth and land, benefiting its nobles, knights, and populace, fostering rapid national development under these circumstances.
The Roman Empire spent approximately twenty years gradually conquering the lands between the Rhine and Elbe rivers, but the newly conquered territories experienced constant uprisings.
Later, the general Varus was ambushed and annihilated in the Battle of the Teutoburg Forest while suppressing a Germanic revolt, forcing Augustus to abandon the territories between the Rhine and Elbe.
From then on, Rome's expansion westward into Germania ceased.
Augustus did not undertake further major campaigns to the west, instead turning his attention eastward.