Ariana per Eratosthenes' definition (19th-century reconstruction of world map by Eratosthenes, c.194 BC).
Ariana, the Latinized form of the Ancient Greek Ἀρ(ε)ιανή Ar(e)ianē (inhabitants: Ariani; Ἀρ(ε)ιανοί Ar(e)ianoi), was a general geographical term used by some Greek and Roman authors of the ancient period for a district of wide extent between Central Asia and the Indus River, comprising the eastern provinces of the Achaemenid Empire that covered the whole of modern-day Afghanistan, as well as the easternmost part of Iran and up to the Indus River in Pakistan (former Northern India).
At various times, various parts of the region were governed by the Persians (the Achaemenids from 550 to 330 BC, the Sasanians from 275 to 650 AD and the Indo-Sasanians from 345 to 450 AD), the Macedonians (the Seleucids from 330 to 250 BC, the Greco-Bactrians from 250 to 110 BC and the Indo-Greeks from 155 to 90 BC), Iranian peoples from Persia and Central Asia (the Parthians from 160 BC to 225 AD, the Indo-Scythians from 90 BC to 20 AD, the Indo-Parthians from 20 to 225 AD and the Kushans from 110 BC to 225 AD), the Xionites (the Kidarites from 360 to 465 AD and the Hephthalites from 450 to 565 AD) and Indian empires (the Mauryans from 275 to 185 BC).
The Greek term Arianē (Latin: Ariana) is based on Aryan, a term found in Iranian Avestan Airiiana- (especially in Airyanem Vaejah, the name of the Iranian peoples' mother country). The modern name Iran represents a different form of the ancient name Ariana which derived from Airyanem Vaejah and implies that Iran is “the” Ariana itself – a word of Sanskrit origin found in Old Persian – a view supported by the traditions of the country preserved in the Muslim writers of the ninth and tenth centuries. The Greeks also referred to Haroyum/Haraiva (Herat) as 'Aria', considered the "Pearl of Ariana" which is one of the many provinces found in Ariana. The surrounding region of Herat (the whole of Afghanistan and Eastern Iran) is considered the true homeland of the Aryan people, which is why modern-day Afghanistan was referenced as Ariana in antiquity, and still used to varying degrees today. 
The names Ariana and Aria, and many other ancient titles of which Aria is a component element, are connected with the Sanskrit term Aryan, the Avestan term Airya-, and the Old Persian term Ariya-, a self designation of the peoples of Ancient India and Ancient Iran, meaning "noble", "excellent" and "honourable".
Extent of Ariana
The exact limits of Ariana are laid down with little accuracy in classical sources. It seems to have been often confused (as in Pliny, Naturalis Historia, book vi, chapter 23) with the small province of Aria.
Per Eratosthenes' definition, the borders of Ariana were defined by the Indus River in the east, the sea in the south, a line from Carmania to the Caspian Gates in the west, and the so-called Taurus Mountains in the north. This large region included almost all of the countries east of Media and ancient Persia, including south of the great mountain ranges up to the deserts of Gedrosia and Carmania, i.e. the provinces of Carmania, Gedrosia, Drangiana, Arachosia, Aria, the Paropamisadae; also Bactria was reckoned to Ariana and was called "the ornament of Ariana as a whole" by Apollodorus of Artemita.
After having described the boundaries of Ariana, Strabo writes that the name Αρειανή could also be extended to part of the Persians and the Medes and also to the northwards Bactrians and the Sogdians. A detailed description of that region is to be found in Strabo's Geographica, Book XV – "Persia, Ariana, the Indian subcontinent", chapter 2, sections 1–9.
Having considered these various sources, Ariana includes Afghanistan (Bactria, Arachosia, Aria, Drangiana, and Paropamisadae), east and southeast Iran (Carmania and Gedrosia), most of Tajikistan (Sogdiana), most of Turkmenistan (Margiana), south Uzbekistan (parts of Sogdiana) and extending to the Indus River in Pakistan (Paropamisadae).
Inhabitants of Ariana
- the inhabitants of Daritis;
Pliny (vi. 23) says that some add to India four satrapies to the west of the river, – the Gedrosii, Arachosii, Arii, and Paropamisadae, as far as the river Cophes (the river Kabul). Pliny therefore agrees on the whole with Strabo. Dionysius Periegetes (1097) agrees with Strabo in extending the northern boundary of the Ariani to the Paropamisus, and (714) speaks of them as inhabiting the shores of the Erythraean Sea. It is probable, from Strabo (xv. p.724), that the term was extended to include the east Persians, Bactrians, and Sogdians, with the people of Ariana below the mountains, because they were for the most part of one speech.
Eratosthenes’ use of this term (followed by Diodorus 2.37.6) is obviously due to a mistake, since, firstly, not all inhabitants of these lands belonged to the same tribe and, secondly, the term "Aryan" originally was an ethnical one and only later a political one as the name of the Iranian empire (for all North Indians and Iranians designated themselves as "Aryan"; See Aryan), thus comprising still other Iranian tribes outside of Ariana proper, like Medes, Persians or Sogdians (so possibly in Diodorus 1.94.2, where Zarathushtra is said to have preached Ahura Mazdā's laws "among the Arianoi").— R. Schmitt, 1986
- Pliny, Naturalis Historia, book vi, page 23
- Smith, William (1980). "Ariana". Dictionary of Greek and Roman Geography. Boston: Little, Brown, and Co. pp. 210–211. Retrieved 2013-05-10.
- Schmitt, R. (1986). "Aria". Encyclopaedia Iranica. Retrieved 2013-05-10.
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- The Columbia Encyclopedia, Sixth Edition, 2008
- Sagar, Krishna Chandra (1 January 1992). Foreign Influence on Ancient India. Northern Book Centre. p. 91. ISBN 9788172110284.
According to Strabo (c. 54 B.C., A.D. 24), who refers to the authority of Apollodorus of Artemia, the Greeks of Bactria became masters of Ariana, a vague term roughly indicating the eastern districts of the Persian empire, and of India.
- Gnoli, G. (2006). "Iranian identity ii. Pre-Islamic Period". Encyclopaedia Iranica. Retrieved 2013-05-10.
- Ashraf, A. (2006). "Iranian identity iii. Medieval Islamic Period". Encyclopaedia Iranica. Retrieved 2013-05-10.
- Ed Eduljee. "Haroyu, Aria / Airan, Herat & Zoroastrianism". Heritageinstitute.com. Retrieved 2016-10-21.
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- Schmitt, R. (1987). "Aryans". Encyclopaedia Iranica. Retrieved 2013-05-10.
- Strabo 2.1.22f
- Strabo 2.5.32
- Strabo 11.11.1
- Gnoli, Gherardo (2002). The "Aryan" Language. Roma: Instituto Italiano per l'Africa e l'Oriente. p. 86.
- "Strabo Geography, Book XV, Chapter 2". Penelope.uchicago.edu. Retrieved 2013-05-10.
- Horace Hayman Wilson, Charles Masson, Ariana Antiqua: a Descriptive Account of the Antiquities and Coins of Afghanistan, 1841
- Henry Walter Bellew, An inquiry into the ethnography of Afghanistan, 1891
- Tomaschek in Pauly-Wissowa, II/1, cols. 619f., and 813f.
- G. Gnoli, Postilla ad Ariyō šayana, RSO 41, 1966, pp. 329–34.
- P. Calmeyer, AMI 15, 1982, pp. 135ff.
- Encyclopaedia Iranica Aria region in the eastern part of the Persian empire
- 'Ărĭāna', Charlton T. Lewis, Charles Short, A Latin Dictionary, Perseus Digital Library.
- 'Ariana', Dictionary of Greek and Roman geography, William Smith, 1870
- 'Stabo GeographyY', Book XV, Chapter 2.
- Pliny the Elder, The Natural History, Chap. 23. (20.)—The Indus, Perseus Digital Library.
- Pliny the Elder, The Natural History, Chap. 25.—The Ariani and the adjoining nations, Perseus Digital Library.
- Pomponius Mela: De Chorographia Liber Primus
- Ariana antiqua: a descriptive account of the antiquities and coins of Afghanistan By Horace Hayman Wilson, Charles Masson
- Eratosthenes, Duane W. Roller, Strabo, 2010, 'Eratosthenes' Geography'