Diplomacy and geographical proximity primarily determined the foreign relations maintained by Asoka. Particularly, the century in which, Asoka lived was one of continued interactions between the Eastern Mediterranean and South Asia. That is why most of Asoka's contacts were with South Asia and the West. It appears that this interest was not one sided. A fair number of foreigners lived in Pataliputra to necessitate a special committee under the municipal management to look after the needs of welfare of the visitors. Apart from these major factors determining the foreign relations of Asoka, one more parameter was the desire of Asoka to spread his policy of dhamma to distant lands.
To begin with, Asoka in his foreign relations was a realist defeat and annexation of Kalinga. Also his realism is to be seen in Asoka not annexing the southern kingdoms (Cholas, Pandvas, Satyaputras and Keralaputras) while being satisfied with theirac knowledgement of his suzerainty. He probably felt that it was not worth the trouble to annex the small territories too.
In other foreign relations Asoka reveals as an idealist or a monarch who wore the robes of a monk. He sent various missions, though not embassies, to various countries. Their main purpose was to acquaint the countries they visited with his policies, particularly that of dhamma. They may be compared to modern goodwill missions helping to create an interest in the ideas and peoples of the country from which they came. Also, the fact that they are quite unheard of in contemporary literature or in later sources would suggest that they made only a short-lived impression.
In spite of the above reservations, the missions must have opened a number of channels for the flow of Indian ideas and goods. It is unlikely that Asoka expected all the kings who had received missions to put the policy of dhamma into practice, although he claims that his did happen. It is curious to observe that there is no reference to these missions in the last important public declaration of Asoka, the seventh pillar edict. In this edict Asoka mentions the success he had with his welfare services and the widespread propagation of dhamma but all within the empire.
The territory immediately adjoining the empire of Asoka on the West and that Antiochus. There is ample evidence of contacts of similarity in cultures. The use of Kharoshti in the Shahbazgarhi and Mansehra edicts in the north is evidence of strong contact with Iran. The fragmentary Aramaic inscription at Taxila and another of the same kind from Kashmir point to continue inter communication between the two areas.
Apart from contacts with Iran, Asoka Empire was close to various Greek kingdoms. There are references to the Greeks in the rock edicts of Asoka. On certain occasions the word used refers to the Greek settlements in the north-west and on others to the Hellenic Kingdoms. Antiochus II these of Syria is more frequently mentioned. He other Hellenic Kings where missions were sent were Ptolemy-II Philadephus of Egypt, Magas of Cyrene, Antigonus gonatas of Messedonia, and Alexander of Eorius.
Apart from these western contacts, tradition maintains that Asoka visited Khotan. This cannot be substantiated. On the other hand, Asoka maintained close relations with modern Nepal. Tradition states that his daughter, Charumati was married to Devapala of Nepal.
On the East, the Mauryan empire included the provice of Vanga, Since Tamralipti was the principal port of the area, Indian missions to and from Ceylon are said to have traveled via Tamaralipti.
The extent of the influence of Asoka's power in South India is better documented than in north India. The edicts of Asoka are found at Gavimathi, Palkignuda, Brahmagiri, Maski, yerragudi and Siddapur, Tamil poets also make references to the Mauryas.
More Important were the contacts with Ceylon. Information is available in the Ceylonese Chronicles on contacts between India and Ceylon. Coming of Mahindra to Ceylon was not the first official contact. Earlier, Dhamma missions were sent. A Ceylonese king was so captivated by Asoka that the top called himself as Devanampiya. Asoka maintained close relations with Tissa, the ruler of Ceylon. Relationship between Asoka and Tissa was based on mutual admiration for each other.
What interests of the country or the aims of Asoka were served through his missions? Asoka primarily tried to propagate his dhamma and may be incidentally Buddhims. He claimed that he made a spiritual conquest of all the territories specified by him as well as a few more territories beyond them. This claim definitely appears to bean exaggeration. There is no historical evidence to show that Asoka missions did succeed in achieving their aim particularly when the dhamma happened to be highly humanistic and ethical in nature. After all, Asoka was neither a Buddha nor a Christ to appeal to various people. Neither a St. Peter nor an Ananda to successful spread the message of their Masters. Not did he possess fighting men to spread his message just as the followers of prophet Mohammed. Thus, when there is no follow up action after the missions visited the various parts of the world, it is understandable that no one paid any heed to his message.
Evertheless, there is one intriguing point about the success of his foreign missions. In likelihood, the history of the Buddha and his message must have spread to the various parts. What did they need to? Although it is difficult to answer this question, it is of importance to observe that there are certain similarities between Christianity and Buddhism - suffering of man, Mara & Satan, Sangha Monasteries with Bikshus and Monks, and the use of rosary by Buddhist and Christian's monks.