Our Journey begins in the southern Steppes of Ukraine roughly 2000 B.C.E., when the Indo-European conglomoration of people's calling themselves Aryans (Arya, Airya, and inaccurately by 19th century scholars termed as Zend) - only lightly steaped in a Bronze Age culture, still heavily utilizing copper and Neolithic tools - actualized the cultural and ethnic differentiations and divisions slowly created throughout centuries in the Indo-European expanse of peoples, splitting south-east and arriving as a powerful new force upon the peoples occupying roughly the region of modern day Iran, its constituent plateau and India. The path of their descent is yet uncertain; it has been long argued that they descended thru the Caucasus, however, evidence suggest that since that time, significant geographical changes occurred concerning the expanse of the Caucasus Sea and the formations of the earth's surface in the region, such that migration through the region by the descending Aryan tribes of the time would have been terribly difficult at the least - as such, Asia Minor has been suggested as an alternate route the Aryans may have descended by.

However, it must be considered that the geographical awareness of the region (Eastern Europe) by the Greeks (namely Ptolemy) who have been utilized as sources for a reconstruction of the region's geography, was not completely accurate. Particularly speaking, this inaccuracy can be traced to Ptolemy's great confusion regarding the shape Eastern Europe was to have. Moreover, when considering the migration patterns later observed from the eastern regions of the Iranian plateau westwardly, ultimately, into the lush lands of Mesapotamia, an eastern route seems more plausible than a migration through Asia Minor, although, by no means is it necessary to accept the Aryan descent as a single monolith surge through that one pass. Surely, the Aryans were a broad classification of peoples and could have easily descended by several routes - through the Caucasus onto the Iranian plateau, and then east into India and west into Mesapotamia, or perhaps around the Caspian sea - eventhough evidence of the terrian about the Caucasus indicates that the Caspian sea at that time extended farther east, making a journey around the Caspian less likely although not impossible - or through Asia Minor, particularly Anatolia, which would account for the early presence (roughly 18th century B.C.E.) of Aryan stock in Mesapotamia.

To further support the Asia Minor hypothesis was the find of a large mass of records at Boghaz Keui, a site east of the river Halys, in 1906-7 containing major archives of the ancient Hittite empire dating from the 15th and 14th centuries B.C.E. They were written in eight languages, two of which had a distinct Indo-European flavour. The forms of these languages were very similar, particularly in the names of the deities and the numerals, to Sanskrit, further correlating this Indo-European influence with the Aryan peoples who had by that time begun their encroachement upon India roughly a century previous to the compilation of these Hittite records and roughly yet another century earlier began penetrating the Mesapotamian region.

These considerations aside, we know that by the first half of the 1st mellenium B.C.E. the Aryans had arrived on the Iranian plateau and the Indian subcontinent. Indeed, the term Iran is the result of the term Ariana (Airyana) meaning "the land of the Aryans." The Aryan group of languages had two principle divisions: Sanskrit and Old Iranian. Of the Old Iranian, the Old Persian and Avestan dialects were the most important - little is known of the other dialects. In Middle Persian, we find the term "Ariana" as "Eran" and in Modern Persian, of course, as "Iran." Avestan, also termed as Zend, was the dialect used in the Avesta, the Zoroastrian holy book.

As the Aryan Indo-Europeans descended onto the Iranian plateau, they divided once again; one group migrated into the Indian subcontinent whilst the other progressed westwardly eventually caressing the borders of the Semitic lands. The eastern group is known to have settled in the Punjab between the Indus and Sarasvati during the Vedic era circa 13th century B.C.E. The literay and linguistic evolution of Sanskrit from its earliest instances in the Rig-Veda to the end of the Vedic era, circa 500 B.C.E. - the time of Buddha and Mahavira - is considerable, but does not suggest a time period of a millenium as is sometimes postulated. More likely a period of about 600 to 700 years between the early Rig-Vedan Sanskrit and the end of the Vedic period is suggested (500 + 700 = 1100 B.C.E. conservative estimate). The Aryans would have arrived, then, behind this time and at least a few centuries earlier as the process of subjugating the Indigenous Indian tribes was completed by the later Vedic period, which can be placed between the 10th and 6th centuries B.C.E., requiring that the date of the initial invasion be alotted enough time such that subjugation of these indigenous peoples can be accomplished by this time: circa 16th century B.C.E. is a reasonable estimate for this event.

Even with this west-east division, the Indian and Iranian groups still maintained a close connexion as is evinced by the similarity of Sanskrit with Old Persian and Avestan; only later did the Iranian and Indian tongues sharply diverge.

The westward movement of the western group of Aryans can be observed to have reached the Semitic lands by the 18th century B.C.E. It is postulated that they migrated westward in the role of mercenaries, as the term Marianni - an Aryan word meaning warriors - can be observed in Egyptian and Hittite texts classifying them as a ruling military class; and documents from the 16th century B.C.E. in Mesapotamia and Syria disclose Iranian names. Morever, the dynasty of the Mitanni kingdom, situated in northern Mesapotamia, can be proved to have Aryan origins by the names of its kings (Artatama, Shutarna, Artasumara, Dushratta) and in a treaty betwixt the Mitanni and Hittites dating to the 15th century B.C.E. the gods Mitra and Varuna, Indra and the Nasatyas are invoked by the former. For the study of Mithraism, this data is vital, as it is one of the earliest recordings concerning the god Mithra, and it clearly indicates his Aryan origin: Mitra (later to be transformed into Mithra) being the Sanskrit counterpart of the Old Persian Mihr (meaning: friend or contract) both derived from the Iranian (Aryan) root Mei meaning "exchange."

Much of the pre-Zoroastrian Iranian Mithra in terms of how he was worshipped by the Iranians is little known. It is known that Mithra boasted a considerable following; there are indications that he was attributed elements of a sky god - he was associated with the sun, altho not equated with it, and was termed the 'god of light' - and was often invoked with other high gods, such as Ahura, who at that time bore a prominent although non-universal position.

The Mitra counterpart in India played an amorphous part along with the other gods (Varuna, Indra, Agni, Vishnu, et cetera) such that even as the Rig Veda, one of Hinduism's holy books, classifies its 33 gods (a number which constantly increases with time) into 3 classes: celestial, aerial, and terrestrial, the gods constantly are found to overlap their jurisdictions. From the etymology of the name Mitra/Mithra it can hypothesized that the god was one of contracts, perhaps, a spiritual moral contract as we find the fussion of Mitra and Varuna into Mitra-Varuna as a deity of moral integrity.

Unfortunately, as the Zoroastrian reformation of the Iranian Pantheon occurred centuries later, the gods would be drastically re-ordered into a new henotheistic heirarchy, and as such, except for glimpses of possible remnants of more ancient beliefs in the Avesta, little else can be gleaned concerning this primitive Mithra.