[kragen]

A thing I was thinking was that, though almost surely the line was broken in the West, it might not have been broken altogether. We know, for example, that the Pauliṣa Siddhānta in India contains Hellenistic astronomy; and we know that as far back as Classical Athens, Greek philosophers reported visiting India and studying with "gymnosophists", an ascetic tradition (called Digambara in Sanskrit) which either survives there today or has been coincidentally reinvented in the same subcontinent at least a thousand years ago. Surely it is conceivable that, during the period when Rome was laying waste to the Hellenistic world, some philosophers might have fled to India and trained their successors there?

But it does seem very unlikely that we could trace it, given how little written material survives from that period in India.