India, China and the African continent today are mostly associated with poverty in Europe, the US and so on. Looking at India specifically, did it during the medieval era share a similar standard of living to England (at the same point in time), and if so when did they start to diverge?
This is partly covered in the article "India and the Great Divergence: An Anglo-Indian Comparison of GDP per Capita, 1600-1871" by Stephen Broadberry and Bishnupriya Gupta.
The article is available here: http://www.lse.ac.uk/economicHistory/pdf/Broadberry/IndianGDPpre1970v7.pdf . (Note that in-progress articles like this have a tendency to disappear from the web over time). The abstract of the article is:
The paper does perhaps not go as far back as you want to, but the literature section contains several references to other studies of living standards in India and Britain. I also suggest you have a look at Broadberry's home page (a very respected economic historian) for more information on related topics: http://www.lse.ac.uk/economicHistory/whosWho/profiles/sbroadberry.aspx
Among these is a paper by the same authors from 2006: "The Early Modern Great Divergence: Wages, Prices and Economic Development in Europe and Asia, 1500-1800", Economic History Review, 59 (2006), 2-31. Abstract:
"Living Standards" require certain
However, if we consider
Another paper which provides several other indicators, also studies the period from 1600 C.E finds a steady decline in per capita GDP while UK's per capita increases steadily in the same period. See page 22, tables 12 and 13. For wages, see page 16, table 3. This paper also mentions several other source material as reference.
Another source which which studies economic history is "World Economic Historical Statistics" by Carlos Sabillon. This book details/charts the changes in GDP and sector-wise contributions (Manufacturing, Agriculture) from 16th century to the 1990s for all regions of the world.
This is really a broad question which probably should be closed, but I will take a stab at it.
First of all, it is hard to compare India to England because India is a much larger place. Comparing India to Europe might be a better comparison.
Many parts of India were probably better off than England between 400 A.D. and 1000 A.D. after that the Moghul invasions made India go downhill and meanwhile things were getting better gradually in England.
So, to pick a date, that would be about 1000 A.D. that was the turning point.