One section stood out as unusual more than the rest...mostly because when I tried to google for more information... NOTHING came up. Even on the PBS website supporting the documentary with extra photos, links and commentary, they had pictures and discussion of the palm leaf manuscripts but nothing about copper plates.
The Story of India: Part 4: Michael Wood documentary
Here in the former royal library is a vast store of Ancient Tamil literature going back to the Cholans and beyond...
grammar, poetry and philosophy.
Many of the texts are preserved on fragile palm leaf manuscripts
which are now being carefully restored.
and one fascinating and little known aspect of their culture is that
the Cholans also wrote their own history.
What would be a manuscript book, a chronicle in Western Europe, say in the 10th and 11th century,
here in the Cholan empire is copper plates.
This is just one document from a temple treasury. About 15 copper plates.
There’s the seal of Rajendra, the son of Raja Raja the Great. The umbrella and the fish , the tiger.
Weighs about 40 kilos.
and there’s thousands of these. thousands of these,
most of them still kept by individual temples.
These things were used for recording
but also history
and they include the history of how Raja Raja the Great, came to the throne.
Now that I have this, I've been able to find a few other links.=>
Wiki link on the use of copper plates for records in India. The earliest is denoted as 'pre-Ashoka Maurya' who lived from 304 BC to 242 BC.