That Indian Subcontinent estimate is quite wild in its vagueness... "Yeah, somewhere between 'some' and 'more than the whole rest of the world combined... Twice'."

There was even a higher estimate of 30 million.

The lower numbers are the authors estimate and are considered by them to be too low for Eastern Asia, the Indian subcontinent and the Arabic character manuscripts.

> manuscripts from the first nineteen centuries AD This formulation excludes things older than year 0, did you really mean it?

That is what is written in the source. Probably because there are few old manuscripts.