Alexander did not leave any corner or pocket unclean earlier included in the political realm of Achaemenians. With this view in mind he crossed Hindu Kush and captured whole of Bactria and Sogdiana (Central Asia) and appointed his own governors there and then came back after crossing Hindu Kush in ten days in the early spring of 327 BCE.
Conquest of Indus Region: Political situation of the Indian Satrapy after the Achaemenians disintegration After the disintegration of Achaemenian empire the Indus Satrapy was no longer united as an administrative entity.
These repeated failures in the battle fields infact had exposed military might and weaknesses of Iranian authority therefore Alexander fearlessly marched on towards Mesopotamia to fight a decisive battle at the historic battle field of Arbela where the last Achaemenian King of Kings" Darius III was utterly defeated by Europeans in 330 BCE.
By that time the Achaemenian Satrapy of Indus Zone was still unconquered by Macedonians however it seems certain that the administration of the defunct Persian empire in the Indus Valley with all probabilities would have practically become disfunctionning.
Alexander, his Seleucid successors, and the flood of Hellenistic culture that swept into Northern India in their wake, did what the Achaemenians had not done--inspire imitators that had absorbed and could apply both Greek and Persian lessons of statecraft.
Between 521 and 519 BCE, the forces of the Achaemenian Emperor Darius I seized the Indus valley, occupying the original heartland of the ancient Harappean civilization.
It is likely that this complex is the oldest surviving Persian building, dating from the Achaemenians in 559 b.c.
The Medeans and Persians were united by Cyrus I, who established the Achaemenian dynasty and laid the foundation of the Persian Empire in 630 b.c.
The next great Achaemenian ruler was Darius, who started building the new capital, Persepolis, with numerous palaces, stables, a treasury, and the great Apadana--a reception hall for ten thousand people.
The city was the capital of the Elamites and subsequently the winter capital of Achaemenians
for some 2800 years.
The Old Persian of the Achaemenian
Empire, preserved in a number of cuneiform inscriptions, was an Indo-European tongue with close affinities with Sanskrit and Avestan (the language of the Zoroastrian sacred texts).
xv: In the chapters that follow, I hope to show how Achaemenian
Persia perceived itself as God's chosen instrument for the project of world salvation, and, as such, supreme benefactor of the peoples it conquered.