In the case of ancient Ariana, they cite Strabo's Geographica book four as their reference, which supposedly marks out the borders of Ariana with accuracy.
The reason for my discussing this is because there has been a new propaganda campaign by Afghans to claim Ariana as the ancient name of Afghanistan. The claim is that the modern Afghan state is nothing more than a continuation of ancient Ariana which has existed for thousands of years.
Using the citation of Geographica on the wiki, I decided to further research this book. According to sources, Geographica was written by Strabo, an educated citizen of the Roman empire. The book itself is supposedly consisted of seventeen volumes and was written no time earlier than 20BC.
Also according to sources, detailed descriptions of Ariana are found in Geographica's book fifteen, chapter two, sections one to nine.
Though I don't posses a hard copy of Strabo's Geographica translated into English (the original version was in Greek), I have found what an online reproduction of the Loeb classical Library edition published in 1932.
Here is a quote I want to share of this translation of Geographica's book fifteen chapter two:
"After India ("India" in this case refers to the name coined for the Indus river region by the ancient Greeks, most accurately the provinces of Punjab and Sindh; not the modern country that is known as India, which took up the name used by the British to refer to the entire subcontinent), one comes to Ariana, the first portion of the country subject to the Persians after the Indus River and of the upper Satrapies situated outside the Tarus. Ariana is bounded on the south and on the north by the same sea and the same mountains as India; and from this river it extends towards the west as far as the line drawn from the Caspian Gates to Carmania, so that its shape is quadrilateral. Now the southern side begins at the outlets of the Indus and at Patelene, and ends at Carmania and the mouth of the Persian Gulf, where it has a promontory that projects considerably towards the south; and then it takes a bend into the gulf in the direction of Persis."
According to this site, the Caspian Gate is mentioned in several ancient sources as a mountain pass on the road between Rhagae in modern Iran and the Parthian capital on the border region between Turkmenistan and Iran.
This coincides with Wikipedia's [sourced] statements that Ariana most likely consisted of Iran and western Afghanistan. Ariana's borders have not yet been strictly defined and they are still disputed amongst scholars.
But in any case the historic consensus is that Ariana cannot have been centered only within Afghanistan and the western Pakistani provinces that Afghans have claimed for decades and still claim.
The above quote from Geographica's fifteenth book and other mentioned/linked sources directly contradict Afghan claims on Ariana being their country's ancient name.
If Afghans are willing to continue making these false claims on being the direct heirs to Ariana, they cannot do so without extending their claims to Iranian territory and parts of Central Asia.
Why should Afghanistan be allowed to claim itself as a modern form of Ariana? Why not Iran or Pakistan or countries on the eastern Caspian sea shores? Given that these territories consisted of the modern countries/territories mentioned?
Already some Iranians claim Afghanistan be be part of "greater Iran" possibly based on the Ariana region.
It is common to see people claiming ancient names of people(s) and places as part of their heritage without any proof or evidence.
Afghans can also be found claiming other historic names of peoples and places for themselves such as claiming descent from the Parthians despite the Parthians having their capitals in Eastern Iran.
Afghans also claim Scythian descent, despite Scythians being a separate Iranic people from Pakhtuns, Tajiks or Persians. The map below shows the spread of the Scythian and Parthian empires mostly over Iran Central Asia as well as Afghanistan, Pakistan and North Western India.
Who are the Afghans to be claiming this all exclusively as part of Afghan history? Most of these mentioned peoples and places are now extinct. Boundaries of states and nations change over time. Races appear and disappear from Earth or assimilate into larger/stronger races forming a new race which is an element of two or more. Good examples of these are the Tocharians forming with Turko-Mongol tribes forming the modern-day Uyghurs.
Or the ancient Europeans who invaded South Asia and mixed with the local population forming the modern-day Pakistanis.
Many Afghans who believe Afghanistan to be ancient Ariana and Pakistan a brand new state only sixty plus years old with no ancient history and holding on to "ancient Afghans lands" are misinformed and don't have a proper insight to the history of the region or just plain ignorant.
By this same token, Pakistan can also lay claims to ancient territories such as Sapta Sindhu, which is the ancient Sanskrit name for most of Pakistan and the Ganges river belt in Northern India which translates to "land of the rivers" since Pakistan and the Ganges valley are home to several rivers. Some are larger, others are smaller.
Recent findings have lead to theories that the ancient Sumerians referred to the Indus Valley/Pakistan as "Melluha" which possibly meant land of the waters, though these are just theories.
All theories and claims by countries over ancient settlements and peoples must be backed up by evidence. Weather this evidence is artifacts, ancient texts, fossils or any other form of evidence.
The Afghan claim over Ariana has none of these, while the idea of Ariana spanning through Afghanistan, across the Middle East/South Asia/Central Asia has plenty of evidence contradicting the Afghan claim, the above information being only one of them.
Many Afghans uneducated in history and other ignorant people think of Afghanistan as some sort of six thousand year-old state. This is possibly because the name "Afghanistan" has been around for two and a half centuries while the name Pakistan has been around for about a little over half a century.
The history of the Afghan state begins in 1747 AD. The country was formed by Ahmed Shah Durrani, a Pashtun leader who conquered various provinces including that of Turkic and Tajik speaking people and forged them into one state.
Ever since 1747 the history of the Afghan state has seen many invasions and wars, which is too long to discuss in detail. The main point is that Ariana is in no way a "predecessor" to Afghanistan, nor is the Afghan state six thousand years old as some of it's people claim.
This post ends with a quote from the CIA world fact book on the background of the the modern Afghan state:
Ahmad Shah DURRANI unified the Pashtun tribes and founded Afghanistan in 1747. The country served as a buffer between the British and Russian empires until it won independence from notional British control in 1919.