Bactria was a homeland of Indo-European tribes who moved south-west into Iran and into North-Western India around 2500–2000 BCE.
"Bakhdhi is the fourth nation in the Avestan Vendidad's list of nations - Airyana Vaeja (homeland of the Aryans) being the first. Bakhdhi is the ancient Avestan name while Balkh is the modern name for both the region and its old capital city. ....During the middle period of Aryan history - as the Aryans moved west from Airyana Vaeja towards present day Iran - Bakhdhi (Balkh as its is known today) became the principle kingdom of the Aryan confederation of kingdoms called Airan, and the eponymous city of Balkh was its capital. As the seat of Aryan rule moved westward to what is the Iranian province of Khorasan today, Balkh became part of greater Khorasan and remained an important regional capital as well as a cultural and trading centre. ...
The Indo-Iranians transferred geographical names from Iran to India as they migrated south about 1400 BC. Indian Sarasvati and Iranian Hara Vaiti for example. (Burrow: 1973..pg 126)...
The author of Vayu Purana uses the name "Kumuda-dvipa" for Kusha-dvipa. Kumuda is also a Puranic name of a mountain forming the northern buttress of Mount Meru, also known as Sumeru (Pamirs). It extended between headwaters of Oxus and Jaxartes. In anterior Epic Age, Kumuda was also the name given to high "table-land" of the Tartary located to north of the Himavata from which the Aryan race may have originally pushed their way southwards into the Indian peninsula and preserved the name in their traditions as a relic of old mountain worship (Thompson). Thus, the Kumuda-dvipa lay close to the Pamirs and, in fact, name Kumuda-dvipa applied to southern territory of Shakadvipa or Scythia. It lay north to Hemavata (Hindukush) and probably comprised Badakshan, Alay Valley/Alay Mountains range, Tien shan, Kerategin and probably extended northwards as far as Zeravshan valley and Fargana.
The Aryans and the Iranians of Bactria, had a lot in common. They spoke the same language, worshiped the forces of nature, such as: Varuna, the shining Vault of Heaven; Mithra, the friendly light of the sun; Vayu; the wind that pushes aside the storms and clears the heaven; Yama, the primeval man, reigning over the blessed souls in paradise. The powers of nature, to them, were the signs of something far more deeply interfused. In their ceremonies they also drunk the sacred Juice, Soma.These two races slowly drifted apart as time went on, for not known reasons.
INDO-EUROPEANS....Aryans. The first Indo-European speakers entered central Europe about 2300 BC. (National Geographic: May 1977, pg 558)....'The appearance of the Indo-Aryans in India around 1500 BC, the waves of invasion into Greece around 1600-1000 BC, and into Anatolia around 2000 BC"..(Lincoln: 1981..pg 181)...'Identifying the Kurgan culture of southern Russia with that of the Proto-Indo-Europeans. Weaponry was highly developed: swords, spears, and arrows, which testifies to a distinctive warrior ideology." (Gimbutas: 1976..pg 289)...The Kurgans were on the steppes of southern Russia in 4000 BC....."Indo-Europeans of the Pazyryk culture"...(Kharatidi: 1996..pg 169)...."Cold forced them to leave Aryan em Vaejo. They moved to Sughda (Soghdiana) and Muru (Margiana). Hostile forces made them go to Balkdhi (Balkh), 'the country of lofty banners'. From Balkh they proceeded to Misaya (Nisa, Nasa). Their migration settled Arachosia, Helmund, Panjab to the east and Tus, Gurgan, Rei, and Gilan to the West." (Sykes: 1958..pg 97)
The Proto-Indo-Europeans in this sense likely lived during the late Neolithic, or roughly the 4th millennium BC. Mainstream scholarship places them in the forest-steppe zone immediately to the north of the western end of the Pontic-Caspian steppe in Eastern Europe. Some archaeologists would extend the time depth of PIE to the middle Neolithic (5500 to 4500 BC) or even the early Neolithic (7500 to 5500 BC), and suggest alternative location hypotheses......By the late-3rd millennium BC offshoots of the Proto-Indo-Europeans had reached Anatolia, the Aegean, Western Europe, Central Asia and southern Siberia.
Bakhdhi would come to be known as Bakhtrish during Achaemenian times (675 - 330 BCE), Bactra city and greater Bactria from the Greek version of its name during Alexander's and the Seleucid occupation (330 - c. 246 BCE), and briefly Takharistan or Toharistan after the overthrow of the Seleucids. In 246 BCE, allied with Parthava (Parthia), Bakhdhi (Balkh) was one of the first Aryan nations to revolt against Seleucid rule. The "great and noble city" as Marco Polo called it, was destroyed by first by the Arabs and eventually by Mongols in 1220CE. Today, the site of the kingdom and its ancient city is called Balkh, and the once mighty kingdom has been reduced to the fairly small province in Afghanistan.
Aryans & Achaemenids....(c. 1500 B.C. - 330 B.C.) Apastoral, cityless, people led by heroic warriors riding two-horsed chariots came out of the north....In the sacerdotal writings of the Vedic Aryans, the Rigveda, we read of the Kubha (Kabul) River and know of their passage through Afghanistan sometime around 1500 B.C. In the related Persian hymns of the Avesta, we read of Bakhdi (Balkh) "the beautiful, crowned with banners" and of Zarathustra Spitama (Zoroaster), the great politico-religious leader who lived in Balkh sometime between 1000 and 600 B.C. The Aryans found the Bactra area ideal for their flocks of sheep and goats. Many settled here and prospered. As the years passed, however, the various Aryan tribes frequently fought among themselves, encouraging the subjugated indigenous tribes to rise in revolt. Predatory raids by bands of horse-riding nomads from across the Oxus added to the turmoil. Keeping the Aryan herdsmen from their grazing lands, the nomads demanded, and began to receive, tribute for grazing rights. Aryan independence seemed doomed. It was then that Zoroaster came forth to exhort the people to unite, in the name of the god Ahuramazda.
"the split occurred when the Aryans were apparently located at around 50 degrees North latitude somewhere in Northern Eurasia. Later, the Iranian-Aryans migrated further Southwards and finally settled in the Iranian Plateau (Persia), while the Indo-Aryans took a different route and finally settled in the Indo-Gangetic Plain of North India. The split was complete, even physically/geographically."
In Europe the first Indo-European tribes to make significant inroads are the Greeks. They move south into Greece and the Aegean from the 18th century BC...
"Long after the separation of the Indo-Aryans and the Aryo-Iranians the connexion between the two branches remained very intimate. The Indo-Iranians possessed an intimate knowledge of the province of Afghanistan, and there are reasons for believing that no definite line of demar- cation existed between the two branches. It has been noticed in the previous chapters that the Kambojas were included in inter the sixteen great nations of Northern India and that they lived to the west of Gandhara, i.e. Peshawar. They spoke a language which is allied more to the Iranian group of Ian- guages than to the Indian. The country which lies on both banks of the River Oxus (Sanskrit Vakshu) is regarded as a part of India in Sanskrit literature and as a part of Iran in Old Persian literature. Bactria was probably Iranian in speech even in the sixth and seventh centuries B.C., but it is called Bahlika, and the people are regarded as Kshatriyas in Indo- Aryan literature. No boundary line between India and Iran was known in Afghanistan, but to the south of that country the borderland which divided the Indo-Aryan from the remnants of the Dravidians in Baluchistan is called Zranka in Persian and Dranga in Sanskrit, both of which mean a boundary. The Indian term Dranganl, which means " fron- tiers " or " boundaries "........http://archive.org/stream/prehistoricancie035069mbp/prehistoricancie035069mbp_djvu.txt
John Hopkins.....Northern New Mexico….November 2013