They took them initially by military force, then governed with provincial governors (Satraps), leaving the various peoples, tribes and cities to govern themselves using their traditional forms of local governance.
After it was established, it attempted to bring peace, prosperity and good government to its inhabitants and provide internal and external security.
It stretched from Libya to Central Asia. It sought to bring security, stability and prosperity to its diverse peoples.
The attempted to bring peace and prosperity to the peoples living within it's Empire, stretching from Libya to Central Asia. They were largely successful, but the ambitions of Macedonia brought it to an end after two hundred years when Alexander the Great conquered it and turned it into an empire of his own and his successor generals divided it amongst themselves and waged war on each other.
He wanted to maintain peace, stability and prosperity within his empire. When the Greek cities within his empire revolted, and the Greek city-states outside his empire supported them, he decided to bring those external cities within his empire so that, under a Persian provincial governor, they would no longer disrupt the Empire.
The empire that threatened the various Greek City States in the 5th century BCE was the PERSIAN EMPIRE. However, it must be made clear that Greece was a number of independent city-states, not a single independent country.
They didn't 'bring them together', they left them alone to get on with their lives. They established Persian provincial governors who provided internal and external security, and supervised the local governments which they left in place. The people got about their lives and traditional culture under this supervision and protection.
An attempt by the Persian Empire to bring the incessantly warring Greek city-states under its control to stop the fighting spilling over into the Persian Empire and damaging its peace and prosperity.
To bring Greek culture to the conquered Persian Empire.
The Battle of Salamis involved the Persian Empire - it was part of the invasion led by King Xerxes to try to bring the Greek city-states under control to stop their internecine warring spilling over into his empire.
Some sided with the Persians, others combined to repel the Persian invasion.
A fifty-year struggle of the Persian Empire trying to incorporate a couple of hundred Greek city-states within its empire to bring peace and prosperity to the eastern Mediterranean. As with all wars, it brought death and destruction.
They were appalled by their constant fighting of each other, and this spilling over into the Persian Empire, harming its peace and prosperity. Therefore they tried to bring the Greek city-states inside the Persian Empire to be able to control their disruptions.
Persia tried to bring the Greek city-states under control to prevent their incessant warfare with each other spilling into and disrupting the Persian Empire.
He was successor to his father Darius as king of the Persian Empire, led a failed invasion of Greece to bring peace to the Middle East, and re-consolidated the Empire.
He defeated the Persian army, but the remaining eastern provinces still held out. It took him several years and a lot of fighting to bring them under control.
He was determined to bring the Greek city-states under a Persian governor to stop their fighting spilling over into the Persian Empire, disrupting the peace he was trying to enforce.
After it was established, it attempted to bring peace, prosperity and good government to its inhabitants and provide internal and external security.