 Raja Porus as an  ancient Saini warrior
Raja Porus as an  ancient Saini warriorColonel James Tod had concluded that Porus  was a Yadava or  Yaduvanshi king and he further added that this conclusion was not based  on any superficial similarity of names but based on a host of other  available facts.
His view is worth a mention in this regard:
 "To  convince the reader I do not build upon nominal resemblance  , when localities do not bear me out, he is requested to call to  mind,that we have elsewhere assigned to Yadus of  the Punjab the honour of furnishing the well known king named Porus; although the Puar, the usual  pronunciation of Pramar, would afford a more ready solution."  
-Annals and Antiquities of Rajasthan, pp 283, By  James Tod, Edition: 2, Published by Asian Educational Services, 2001
 Tod  went on further to specifically point out Shoorsainis as the Puru tribe  whose king was called Porus, the legendary Indian adversary of  Alexander the Great:
“ Puru became the  patronymic of this branch of the Lunar race. Of this Alexander's  historians made Porus. The Suraseni of Methoras (descendants  of the Soor Sen of Mathura) were all Purus, the Prasioi of  Megasthenes... ” 
- Annals  and Antiquities of Rajast'han, James Tod, pp 36, Published by  Higginbotham and co., 1873
This theory of Tod enjoys a  general consensus in academc community.  Dr. Ishwari Prasad, Dr. Pritam  Saini et al and a number of other history scholars from Indian History  Congress either  have backed this theory  in  entirety or strongly  indicated a link of his army with the Shoorsainis of Mathura.
The Sourasenoi of  Megesthenes 
Ancient Greek traveller and ambassdor to India, Megasthenes,  came  across Saini clan in its glory days as the ruling tribe with its capital  in Mathura.
Megasthenes described this tribe as Sourasenoi  and their patron deity and ancestor as Herakles:
"..This Herakles is held in special  honour by the Sourasenoi, an Indian tribe, who possess two large  cities, Methora and Cleisobora"  Arrian, Indika, viii, Methora is  Mathura ; Growse (Mathura, 3rd ed. 279) suggests Cleisbora is  Krisnhapura , ' city of Krishna'..."
-ANNALS  AND ANTIQUITIES OF RAJASTHAN, James Tod, Vol. 1, pp 36, Oxford  University Press, 1920 
In this article we make  a bold claim that Raja Porus was  a Saini. We back  up this claim with a  solid textual theory developed by Colonel James Tod and accepted well  in the academy. Dr. Pritam Saini, an eminent historian and literary  critic of Punjab, a research fellow at Punjabi university , Patiala ,  a notable journalist and a life long  member  of prestigious  academic bodies like Punjab History Conference and Indian History  Congress, had concluded that Raja Porus was was a Saini and was in the  line of Maharaja Shoor Sen and Krishna-Balram Yadava warrior duo. 
Meaning of Porus as King of  Easterners, or Prachayas, the migrants from East to Punjab and  Afghanistan
The interpretation of 'Prasioi'  as  'Prachaya' , which is an interpretation no historian of repute is  able to disregard, also perfectly jives with  the narratives of  descendants of Shoorsen having migrated westward to Punjab and  Afghanistan after Mahabharata war and the fact that Porus' army carried  an effigy of Balarama or Krishna, the traditional deities of Shoorsainis  who originated from Mathura. A migrant form eastern states is called  "Poorvi" even to this date in Punjab. 
 To  recapitulate all the points discussed so far,  it  did not surprise Col. Tod and other historians of repute who adopted his  analysis to observe that:
1)  Some of the descendants of Shoorsen , i.e. Shoorsainis had moved to  Punjab after Mahabharata war;
2) The  Shoorsainis were called 'Prasioi' or 'Prachaya', or 'Easterners'   because they had migrated to Punjab from Mathura which is in the east of  Punjab;
3) The etymology of 'Porus' is  derived from 'Prasioi' or 'Pracahaya', or 'Easterner', not from  'Paurava', or the descendant of Puru.
4)  The frontline soldiers of Porus carried an effigy of either Balarama or  Krishna, i.e Indian Herakles,  who were both ancestors and patron  deities of Shoorsainis;
5) Megesthenes had  clearly noted that Herakles was held in special regard by 'Sourasenoi'   or Shoorsainis of Mathura when he had visited the place after in around  300 BC as the ambassdor of Seleukos Nikator.
All of the above facts lined up perfectly to support the  conclusion that Porus was a Yadava, or Shoorsaini, the descendant of  Maharaja Shoorsen of Mathura. When Col Tod makes the observation that  Porus was a Shoorsaini  , he has been through an arduous process  of synthesizing   epical references , local etymologies , traditional  legends and  situational issues with the accounts left by the Greek  observers.