Enormous region lying (roughly) between the Oxus (Amu-Darya) to the north and the Hindu Kush to the south; the term occasionally also includes Sogdiana to the north (Tadjikistan/Uzbekistan). The Achaemenid satrapy (Bāxtriš) is cited several times in the Persepolis tablets. Because of the silence of the classical sources, Bactrian history only becomes more fully recoverable with Alexander (3) the Great, who had to fight tough battles here. The discovery of 30 parchments and 18 wooden boards from the late Achaemenid period (Artaxerxes (3) III to Alexander (3) the Great), including two possibly dating to the 5th cent. (as well as palimpsests), written in Aramaic, is now revealing some details of the Achaemenid administration of the region (Bagavant, governor of Khulmi, under Akhvamasda, satrap of Bactria) and Persian-held domains. Recent excavations have profoundly enhanced our knowledge, especially excavation of the site of Ai Khanoum, a Hellenistic city, (possibly) founded by Alexander himself, on the upper Oxus (Alexandria Oxiana?). Surveys in eastern Bactria, on both banks of the Oxus, have revealed that the agricultural prosperity, for which the country was famed, goes back to the bronze age. From this time on, networks of irrigation canals were constructed, which were maintained and extended throughout the Achaemenid and Hellenistic periods. Under the early Seleucids, Bactria was extensively colonized, and Bactra (mod. Balkh) served as a temporary residence for Antiochus (the future Antiochus (1) I), son of Seleucus (1) I. Inscriptions found on several Bactrian sites have provided new insights into Iranian and Greek settlement and into the process of acculturation. A Graeco-Bactrian kingdom was created by Seleucid breakaway satraps. This secession is generally thought to have been achieved by Diodotus (1) c.230 bce, linked to the invasion by the Parni (see parthia) of the Iranian plateau, but this chronology is debated. In 206, following a campaign by Antiochus (3) III, the Graeco-Bactrian king Euthydemus (2) I accepted Seleucid supremacy. In the reign of Eucratides I, people from beyond the Oxus invaded Bactria and destroyed the city of Ai Khanoumc.145 bce. At the end of Heliocles' reign (c.130 bce), another invasion virtually obliterated the Greek presence in Bactria.