History of Afghanistan

Pre - Islamic period

Alexander the Great,
Mauryan rivalry and Greco-Bactrian rule 330 BC – 150 BC
It had taken Alexander only six months to conquer Iran, but it took him nearly three years (from about 330 BCE–327 BCE) to subdue the area that is now Afghanistan. Moving eastward from the area of Herat, the Macedonian leader encountered fierce resistance from the local tribes of Aria (West Afghanistan), Drangiana (now part of Afghanistan, Pakistan and Eastern Iran), Arachosia (South and Central Afghanistan) and Bactria (North and Central Afghanistan). In a letter to his mother, Alexander described his encounters with the western and northern afghan tribes  thus: "I am involved in the land of a 'Leonine' (lion-like) and brave people, where every foot of the ground is like a wall of steel, confronting my soldier. You have brought only one son into the world, but everyone in this land can be called an Alexander!”
 Local resistance and the difficult terrain made it difficult for Alexander's forces to subdue the region as many invaders have found the mountainous terrain of Afghanistan similar to a maze that often trapped outside invaders.

   Alexander the Great fighting the Persian king Darius (Pompeii mosaic, from a 4th century BC original Greek painting, now lost).

Mauryan Period (305-180BCE)
The founder of the empire, Chandragupta Maurya, confronted the Macedonian invasion force led by Seleucus I in 305 BC following a brief conflict, an agreement was reached as Seleucus ceded Gandhara and Arachosia (around ancient Kandahar) and areas south of Bagram (south-east of modern Afghanistan) to the Mauryans. During the 120 years of the Mauryans in southern Afghanistan, Buddhism was introduced and eventually become a major religion alongside Zoroastrianism beliefs and Aramaic was spoken by the Mauryans.

Greco-Bactrian rule 170 BC
In the middle of the 3rd century BC, an independent, Hellenistic state was declared in Bactria and eventually the control of the Seleucids and Mauryans was overthrown in western and southern Afghanistan. Greco-Bactrian rule spread until it included a large territory that stretched from northeastern Iran in the west to the Punjab in India in the east by about 170 BC. Graeco-Bactrian rule was eventually defeated by a combination of inter disputes that plagued Greek and Hellenized rulers to the west, continual conflict with Indian kingdoms.

The Kushan Empire, ca. 150 BC–300 BE
In the third and second centuries BC, the Parthians, a nomadic Iranian people, arrived in ancient Afghanistan. The Parthians established control in most of what is Iran as early as the middle of the 3rd century BC but about 100 years later another Indo-European group from the North, the Tocharian Kushans, entered the region that is now Afghanistan and established an empire lasting almost four centuries.
The Kushan Empire spread from the Kabul River valley to defeat other Central Asian tribes that had previously conquered parts of the northern central Iran once ruled by the Parthians.
It was during his reign that Mahayana Buddhism, imported to northern India earlier by the Mauryan emperor Ashoka (ca. 260 BC–232 BC),

The Shahi Kings
The Shahi dynasties ruled areas of  Kabul Valley (eastern>Afghanistan) and the old province of Gandhara (northern Pakistan and Kashmir) from the decline of the Kushan Empire in 3rd century to the early ninth century. They are split into two areas as the Buddhist Turk-Shahis. (also known as the Kushano-Hephthalites and the later Hindu-Shahis) The change-over occurred around 870, and ruled up until the Islamic conquest of Afghanistan.
The last Shahi emperors Jayapala, Anandapala and Tirlochanpala fought invading Muslim Turks from Central Asia and were gradually defeated and eventually exiled from their domains into northern India.