History of Afghanistan
Macedonian Invasion & Seleucid Empire in Bactria

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The Achaemenid Empire fell to Alexander the Great, leading to the retreat and eventual defeat of its last ruler, Darius III. Seeking refuge in Balkh, Darius III was assassinated by Bessus, a Bactrian noble who then declared himself Artaxerxes V, ruler of Persia. However, Bessus could not withstand Alexander's forces, fleeing back to Balkh to gather support. His efforts failed when local tribes handed him over to Alexander, who had him tortured and executed for regicide.
After subduing Persia, Alexander the Great advanced eastward where he faced resistance from the Kamboja tribes, notably the Aspasioi and Assakenoi, during his invasion of what is now eastern Afghanistan and western Pakistan.[5] The Kambojas inhabited the Hindukush region, an area that has seen various rulers including the Vedic Mahajanapada, Pali Kapiśi, Indo-Greeks, Kushans, Gandharans, to Paristan, and is presently divided between Pakistan and eastern Afghanistan. Over time, the Kambojas assimilated into new identities, though some tribes today still preserve their ancestral names. The Yusufzai Pashtuns, Kom/Kamoz of Nuristan, Ashkun of Nuristan, Yashkun Shina Dards, and the Kamboj of Punjab are examples of groups retaining their Kamboja heritage. Additionally, the country of Cambodia's name is derived from the Kamboja.[6]
Alexander died in 323 BCE at 32, leaving an empire that, due to lack of political integration, fragmented as his generals divided it among themselves. Seleucus, one of Alexander the Great's cavalry commanders, assumed control over the eastern territories after Alexander's death, founding the Seleucid dynasty. Despite the Macedonian soldiers' desire to return to Greece, Seleucus focused on securing his eastern frontier. In the 3rd century BCE, he relocated Ionian Greeks to Balkh among other areas, aiming to strengthen his position and influence in the region.
The Maurya Empire, led by Chandragupta Maurya further entrenched Hinduism and introduced Buddhism to the region, and were planning to capture more territory of Central Asia until they faced local Greco-Bactrian forces. Seleucus is said to have reached a peace treaty with Chandragupta by giving control of the territory south of the Hindu Kush to the Mauryas upon intermarriage and 500 elephants. Afghanistan's significant ancient tangible and intangible Buddhist heritage is recorded through wide-ranging archeological finds, including religious and artistic remnants. Buddhist doctrines are reported to have reached as far as Balkh even during the life of the Buddha (563 - 483 BCE), as recorded by Husang Tsang.