I came across an interesting passage as I was browsing J.P. Mallory and D.Q. Adams' The Oxford Introduction to Proto-Indo-European and the Proto-Indo-European World (2006):
Aryan god ( *h4eros). A deity in charge of welfare is indicated by a number of lexical correspondences (Skt Aryaman, Av airyaman, Gaul Ariomannus, OIr Eremon, and non-cognate functional correspondences, e.g. Vidura in the Mahabharata. The Aryaman-type deity is associated with building and maintenance of roads or pathways, with healing, especially involving a ritual where cattle urine or milk is poured in a furrow, and the institution of marriage. In this sense he is seen as a 'helper' in to the First Function deity of the Mitra type."
The authors however do not include a reference to the Germanic Irmin which I have already established in earlier articles on this blog to be cognate with Aryaman, Airyaman, Ariomannus and Eremon. http://aryan-myth-and-metahistory.blogspot.co.uk/2012/08/aryamanairyamanariomanuseremonirmin.html
Interestingly both Aryaman and Irmin are closely associated with the Milky Way or Irmin's Way. It should be noted that whilst Professor Mallory is an archaeologist and an expert on Proto-Indo-European I am not aware that he is a specialist in comparative mythology. Jaan Puhvel however is such an expert:
"There is more congruence between *Tiwz and *Wodanaz and the Vedic Mitra-Varuna pair as the benevolent contractual patron coupled with the devious and sinister binder-god. There may even be a Germanic parallel to Mitra: Aryaman (and Nuada: Eremon in chap 10) in the Saxon coexistence of Saxnot and Irmin (a god whose name occurs in Irminsul, the cultic pillar razed by Charlemagne, and in Old Saxon Irmintheod 'mankind', literally 'Irmin's people'; cf. aryaman-in chap. 4)." (Comparative Mythology, 1987)
Let us explore in more detail the functions of this Aryan God:
"The king of the Sons of Mil, Eremon, is etymologically the equivalent of the Gaulish Ariomanus, reflecting the same personified *aryomn 'Aryanness' as is seen in the Vedic Aryaman and the Iranian Airyaman. In addition, very specific traits connect Eremon with both of the latter. The dossier of Eremon in the Lebor Gabala involves his role as builder of causeways and royal roads. In the Historia Britonum of Nennius, the Book of Leinster, the Book of Lecan, and some other scources, Eremon arranged a protection against poisoned enemy arrows that consisted of pouring cow's milk into furrows on the battlefield. He also provided wives to his allies and arranged for hereditary succession in favour of the Irish, hiw own people." (Puhvel)
Professor Puhvel goes on to explain that Eremon's functions mirror those of Aryaman in the Rig Veda so this deity was not only etymologically cognate with Aryaman but functionally cognate as well. Thus we can be assured that as He is known in both the Celtic (Irish and Gaulic) and Indo-Iranian worlds He must be traceable back to Proto-Indo-European or Aryan times, thus a prehistoric deity of great antiquity. The Eddas are silent about this God as He appears by the time of their writing to be known only to the southern Germanic peoples. However as Aryaman was a road builder amongst other things we have a similar concept in Irmin as God of the Milky Way, the path that leads from Midgarth to the world of the Gods that the Einheriar must tread after death.
In addition to being the personification of Aryanness He is also regarded by Puhvel as "the personification of Aryan family solidarity". He is thus a racial God.