Dear Piya,
I should have understood that below-quoted 500-years segmentation
for different phases of Buddhism is for the convenirnce of your
explanation about your proposed conclusions.

>>> Edward Conze, in his History of Buddhism, conveniently divides
>>> Buddhist history into four 500-year periods:
>>> 500-0 BCE: Early Buddhism
>>> 0-500 CE: Mahayana
>>> 500-1000: Tantra and Chan
>>> 1000-2000: Modern Buddhism

Since there are so many respectful & venerable bhikkhus and
honourable scholars on the member list of this group, I am still
over-concerned against this segmentation. It is somewhat impressive
and ignore the time delay of different type of Buddhism such as
Original Buddhism, Sectarian Buddhism, Mahayana Buddhism, Tantra
Buddhism, and modern Buddhism. It also simplified the regional
differences, such as Mahayana Buddhism touched down in Sri Lanka,
and dismissed from Sri Lanka somewhere around AD 420??~~500??, to my
best knowledge, Mahayana and Tantra Buddhism never came back to Sri
Lanka until late 20th century. It might also lead the other readers
to ignore the dismission of Buddhism in India.
I say "Nay" to this segmantation.

>>> Conze's fourth period (1000 years) can be again conveniently
>>> divided into two 500-year periods: the fourth 500 then would
>>> be dominated by Buddhism slowly reaching the west.

I do not agree above statements if we mean Mahayana and Tantra
Buddhism in the period of AD 1000 ~~1500 (as proposed the fourth 500-
years.)

To us, puthujjana Buddhist in Taiwan, we are facing another 500-
years segmentation which might have lasted since AD 100. It said the
first 500 years is the intrinsic-dhamma period, they are almost 100%
the same as Buddha's original teaching, the second 500-years period
is similar-dhamma period, it might be less than 80% similarity
against original teaching, the third period is thereafter, so-call
dhamma-ending period. Taking into consideration of dhamma-ending
period, some (sigh, almost 80 %) serious Buddhist teachers (ordained
or upasaka), are convincing lay people and bhikkhu to take quick and
reliable (also intensively faith-orientated) approach for Salvation
instead of enlightment.

For this kind of 500-years segmentation, I would also like to
say "Nay". Buddha's teaching should be timeless and helpful for all
the time period as discussed in S1.2.10 Samiddhi.

Sorry to sidetrack your discussion.

Yifer