Arjunayana, Arjunavana, Arjunavayana or Arjunayanaka was an ancient republican people located in Punjab or north-eastern Rajasthan. They emerged as a political power during the Shunga period (c. 185 – c. 73 BCE). In the Allahabad Pillar Inscription of Samudragupta (c. 335 – c. 380 CE), the Arjunayanas figure among the autonomous political communities bordering on the Gupta Empire who accepted the overlordship of Samudragupta. They are also mentioned in Bṛhat Saṃhitā of Varahamihira (6th century CE). According to Dr Buddha Prakash, the Arjunayanas are mentioned as Prajjunakas in Kautiliya's text Arthashastra which also places them in the northern division of India. Vincent Smith locates their republic in Alwar and Bharatpur states now in Rajasthan, a view which has been rejected by R. C. Majumdar. They are mentioned in the literary sources in Afghanistan from 4th century BCE and after Alexander's invasions in 3rd century they have been mentioned in Agra, Mathura and Southern Haryana region till 4th century CE where their coins have been found too.
The origin of the Arjunayanas is shrouded in obscurity. In terms of literary evidence, Arjunava is mentioned as geographical term in Ganapatha (IV.2.127 dhuma-aday-ah) in Pāṇini (c. 600 BCE to 400 BCE). In terms of excavated archaeological evidence, they make their first appearance in history sometime after the invasion of Alexander and were first attested by their coins belonging to 2nd or 1st century BCE.  Arjunavana is derived from Arjunava. Arjunayana is same as Arjunavana or Arjunavayana. Arjunavana is believed to be derived from Arjunava, a composite of Arjuna and nava (young, modern or descended from).
Greek chronicler Arrian attests one city which he calls Arigaeum or Arigaeon/Arigaion which commanded the road between Kunar and Panjkora valleys in north-eastern Afghanistan. It was in the Kamboja region and the habitat of the Aspasioi tribe (Aśvakas) whom Arrian calls Indian barbarians. These people had given a tough fight to Alexander in 327 BCE and when the defense of their citadel became difficult in view of the superior forces of Alexander, the inhabitants of Arigaeum/Arigaion had deserted the city, set it on fire and retreated to mountainous fastnesses. Alexander took his forces towards the mountainous fastness where most of the Arigaionians (inhabitants of Arigaion) were collected. A hard contest ensued with the Arigaionian Aspasians, both from the difficult nature of the ground and because the Aspasian Indians were not like the other barbarians of this district but were far stronger than their neighbors. Ptolemy attests that Macedonian forces captured about 40,000, and that over 23,000 of which Alexander picked out the finest and sent them into Macedonia. Scholars like Dr V. S. Agarwala have equated the Arigaeum or Arigaion of Arrian to Sanskrit name Arjunava which finds mention in Pāṇini's Ganapatha  as well as in the Kasika. If this interpretation of scholars like Dr V. S. Agarwala is correct and the "Arjunava" of the Kashika or Pāṇini's Ganapatha is indeed the "Arigaeum/Arigaion" of Arrian, then the probable origin of the Arjunayanas can possibly be speculated. The section of Aspasian people inhabiting the city of Arigaion (Arjunava) were probably known as Arjunavanas, Arjunavayanas or Arjunayanas (from Arjunava).
A variant of Sanskrit Arjunayana is attested as Arjunayanaka. Kautiliya's Arthashastra (c. 200 BCE to 300 CE) mentions and brackets a nation called Prajjunaka with Gandhara  and refers to their buffoons, Artisans and professional singers and actors. Since Gandhara was a great ancient cultural center, therefore, the Prajjunakas who are bracketed with the Gandharas and are attested to have Gandhara-like cultural characteristics, must also have laid close to Gandhara. The Prajjunakas of Arthashastra have been supposed by some scholars to be a variant of Sanskrit Arjunayanakas (Arjunayana). If this be correct, then the 4th-century BCE text on statecraft also attests the Arjunayanas (Arjunavanas) as close neighbors of the Gandharas which fact possibly alludes to the inhabitants of Arigaion (Arjunava) of the Swat/Kunar valleys.
It is conceivable to infer that after suffering serious defeat at the hands of Alexander's Macedonian forces in 326 BCE, a section from the Arigaionians had left their old habitat between Swat and Kunar valleys, crossed the Punjab rivers and moved to Punjab and beyond to avoid further persecution by Alexander. 3rd century Buddhist tantra text Mahamayuri attests one place name Arjunavana which is presided over by Yaksha Arjuna. The same text also says that Duryodhana was the tutelary Yaksha of Srughana (modern Sugh in Yamunanagar). On the basis of the Mahamayuri, it has been speculated that the place name Arjunavana of the Buddhist text may have been somewhere near to Srughana (Yamunanagar in Haryana). It has been located somewhere within the triangle formed by Delhi-Jaipur and Agra regions. It is possible that the splinter group from the Arigaion (Arjunava) had moved to and settled in south-east Punjab and Rajasthan under pressure from Alexander and they probably named the political headquarters of their new-found territory also as Arjunavana (from Arjunava) which name finds reference in the 4th century CE Buddhist tantra text Mahamayuri. Arjunayanas of the coins have been identified by Fleet with the Kalachuris who traces their descent from Kartavirya Arjuna of the Haihaya tribe of the antiquity. Some other scholars like Dr Buddha Prakash however like to connect Arjunayanas to Pandava-hero Arjuna.
The findspot of Arjunayana coins indicates that their territory lay within the triangle formed by Delhi-Jaipur-Agra. The Arjunayana coins resemble those of the Yaudheya coins which show their contemporariness. They are several varieties. In one type, the obverse shows a bull and a standing goddess on the reverse. On another type, bull is standing before a tree in railing on the obverse and another bull facing a linga symbol and also carrying a legend Arjunayanajaya on the reverse. The third variety has a bull in the obverse and a swastika with taurine symbol at the end of arms and a branch or palm leaf and the legend Janayana on the reverse. These coins show that these people were devotees of the god Shiva. Now Shiva was the god of the North and also of the Ashvaka land as is attested by Greek chroniclers. With the interpretation of Arrian's Arigaum/Arigaion with Sanskrit Arjunava as suggested by scholars, the possible origin and descent of Arjunayanas can possibly be traced to this Arigaion (Arjunava) of Swat/Kunar regions and possibly be connected with the Ashvakas of the Indian texts. Like Arjunayanas, the Ashvakas (Aspasioi and Assakenoi) were also a republican people as has been attested by Greek chroniclers. The Ashvakas are believed to be a section of the ancient Kambojas. They are mentioned as Ashvayanas and Ashvakayas by Pāṇini. That the Arjunayanas were devotees of god Shiva also alludes to their possible connections with the Swat/Kunar valley, the land of the Ashvakas.
2nd-century coin evidence attests that the Arjunayanas and Yaudheyas were neighbourly tribes and had collaborated in their joint fight against the foreign invaders like the Yavanas, Sakas, Pahlavas and later the Kushanas. Thus, some people speculate that Arujayanas and Yaudheyas may have been allied or related tribes. The Adiparva of Mahabharata references Yaudheya as the son of the Pandava, Yudhishthira. Based on these references, these scholars have speculated that Yaudheyas had descended from, Yaudheya, son of Yudhishtra. And similarly, it has also been speculated that Arjunayanas had also probably descended from Pandava hero, Arjuna. This view is purely mythical and anachronistic. The Yaudheyas as a full-fledged tribe had participated in the Kurukshetra war on the side of Kauravas, the enemies of Pandavas. Furthermore, prior to Kurukshetra war, the Yaudheyas, together with other Punjabi tribes like the Sibis, Trigartas, Rajanyas, Madras, Kekayas, Ambasthas, Kaukuras etc., had joined the Rajasuya ceremony of the Pandavas and had brought tributes to Yudhishtra. Thus, the claim that Yaudheyas had descended from Yaudheya, son of Pandava Yudhishtra is utterly baseless. Similarly, there is no basis, whatsoever, in the speculation that Arjunayanas may have descended from the Pandava hero Arjuna. These seem to be merely fantastic myths invented at later time to connect the Yaudheyas as well as the Arjunayanas to the heroic Pandava lineage. The Arjunayanas are not mentioned in the Mahabharata, Ramayana or any Vedic texts. While Yaudheyas are mentioned in the list of Ayudhajivi Samghas of Pāṇini, the Arjunayanas don't find any reference as such. It may also be a mere speculation that the Prajjunakas of Kautiliya's Arthashastra  are same as Arjunayanas (or Arjunayanakas). Thus, the Arjunayanas/Arjunavanas or Arjunayanakas are, in all probability, a post-Alexandrian phenomena and it is highly likely that this people had been fugitives from the Arigaion (Arjunava) region of the Kunar/Swat valleys.
The territory of the Arjunayanas bordered on the Gupta empire. They are recorded in the Allahabad Pillar inscription of Samudragupta (c. 335 – c. 380 CE) and are mentioned together with Malavas, Yaudheyas, Madrakas, Abhiras, Prarjunas, Sanakanikas, Kakas, Kharaparikas and other tribes. They are believed to have been vanquished by Samudragupta, around 335 CE and amalgamated into the Gupta empire.
(Lines 22–23) (Samudragupta, whose) formidable rule was propitiated with the payment of all tributes, execution of orders and visits (to his court) for obeisance by such frontier rulers as those of Samataṭa, Ḍavāka, Kāmarūpa, Nēpāla, and Kartṛipura, and, by the Mālavas, Ārjunāyanas, Yaudhēyas, Mādrakas, Ābhīras, Prārjunas, Sanakānīkas, Kākas, Kharaparikas and other (tribes)."