In c. 781 Alcuin sent what he called a small gift to Charlemagne. It took the form of two collections of letters supposedly exchanged between ancient figures: a correspondence between the Roman philosopher Seneca and the apostle Paul, and a correspondence between Alexander the Great and Dindimus, king of the Brahmans. Alcuin's dedicatory epigram is the earliest surviving reference to what came to be known as the Collatio Alexandri et Dindimi, an imaginary correspondence in which Alexander and Dindimus debated the moral superiority of their kingdoms. The Brahmans led a proudly ascetic life, whose excessive rigours Alexander rejected as a form of dementia.

Although Alcuin's dedicatory epigram is the earliest reference to the Collatio and the oldest surviving copies date from the ninth century, it was not a Carolingian composition. Scholars roughly agree that it was written between the later fourth and sixth centuries. Interpretations of its original purpose – in effect, whether Alexander or Dindimus (or neither) was meant to be the winner in this epistolary contest – have varied remarkably. The Collatio has been read as an attack upon Alexander by late antique Cynic philosophers; as an attack on the austerity of the Cynics parodied in the figure of Dindimus; as an anti-ascetic tract associated with the likes of Jerome's bête noire, Jovinian; and as a late antique Christian attack on Alexander. The history of the Brahmans’ reputation and medieval reception of the Collatio is much clearer. Already in Late Antiquity the Brahmans enjoyed a laudable reputation among Christian writers and later medieval intellectuals would regard Dindimus as the ‘virtuous heathen par excellence’. Alcuin was very much aligned with this historical trajectory. Making no mention of Alexander he drew Charlemagne's attention to the Brahman people, the gens Bragmana, which ‘stands out for its admirable ways’ and in which a ‘reader can see faith with his mind’.

What would Charlemagne have made of the gens Bragmana? The Brahmans lived out an equality of poverty. Their temples were not adorned with precious metals and gems. They took bodily renunciation so seriously that they refused to rely on medicinal herbs to cure ailments. Charlemagne might have found the Brahman approach to warfare and law-making especially alien. The Brahmans were staunch pacifists and shunned all legislation because laws educated people in the crimes they were meant to prohibit.