[3] The ancient region of Arachosia can be geographically defined as the territory within the drainage basins of the Helmand, Arghandab, Tarnak, and Arghestan rivers: in the north, it incorporated the area surrounding Ghazni; to the south, it was bordered by the Registan desert in the region of Gedrosia; in the west lay the border with Drangiana; and its eastern frontier probably lay at the Bolan Pass.

[4] Arachosia (Old Persian Harauvatiš) had been one of the most important regions of Afghanistan since the Bronze Age, when Helmand culture (c. 3300 – c. 2500 BC) was centred on the site of Mundigak.

[7] In the mid-sixth century BC, Arachosia fell under the control of the nascent Persian Achaemenid Empire; under their rule, the settlement at Kandahar was expanded and rebuilt so that it was divided into quarters by inner walls, while a large citadel was also constructed by hand.

[12] His quick traverse of the region, which he left in late November, suggests that the Kandahar site was not strongly held, with Bessus having withdrawn eastwards.

[18] Alexander probably gave orders to refound the city while he was in Arachosia in late 330 BC or shortly afterwards; it is impossible to say where the garrison of 4,000 infantry and 600 cavalry he left behind in the region was located.

Arrian, Anabasis Alexandri[20] The remains of Alexandria in Arachosia are today found in the tell of Old Kandahar citadel in the western portion of the modern city.