St. Augustine is a very influential figure in Western Christianity. Partly this is surely due to the fact that the Latin Church favored a doctor who was of their own cultural persuasion, schooled in their mores and folkways, as opposed to the ‘logic-choppers’ of the Greek world. In the intellectual Protestant tradition his influence on Martin Luther and John Calvin is well known.
But it was only recently that I realized St. Augustine may have been moderately familiar with the Dharmic tradition. If you recall, he was a Manichaean for some years in his youth. This religion of Persian provenance is relatively well known has having an expansive geographic reach. The last self-conscious Manichaeans probably lived in China in the years around 1500 AD. But in Late Antiquity Manichaeanism apparently had a presence in the Western Roman Empire.
In any case, though notionally a dualistic religion, Manichaeanism acknowledged a strong influence from the Dharmic tradition, in particular Buddhism. Buddha is explicitly mentioned in Manichaean , and noted as a one of the prophets. This is not surprising, as the religion emerged in a diverse and pluralistic Late Antique Persian Empire which ruled over many Buddhist and Hindu peoples on its northern and eastern fringes.
I am not claiming that Buddhism had any direct impact on St. Augustine. But simply putting this into the record to remind ourselves that the extent of what we know about the ancients is pretty limited.