Origen stated that Buddhists co-existed with Druids in pre-Christian Britain: "The island (Britain) has long been predisposed to it (Christianity) through the doctrines of the Druids and Buddhists, who had already inculcated the doctrine of the unity of the Godhead" (Commentary on Ezekiel).
Hippolytus knew of the Indian Brahmins and includes their tradition among the various sources of heresy: “There is . . . among the Indians a heresy of those who philosophize among the Brahmins, who live a self-sufficient life, abstaining from (eating) living creatures and all cooked food … They say that God is light, not like the light one sees, nor like the sun nor fire, but to them God is discourse, not that which finds expression in articulate sounds, but that of knowledge through which the secret mysteries of nature are perceived by the wise” (Adv. Haer).
Scythianus was an Alexandrian religious teacher who visited India around 50 CE. He is mentioned by several Christian writers of the 3rd and 4th centuries CE, including Cyril of Jerusalem, Hippolytus and Epiphanius. Cyril of Jerusalem says this of his pupil Terebinthus: “But Terebinthus, his disciple in this wicked error, inherited his money and books and heresy, and came to Palestine, and becoming known and condemned in Judaea he resolved to pass into Persia: but lest he should be recognised there also by his name he changed it and called himself Buddas." (Catechetical Lecture 6.23)