Why the West? I do not think there is any other historical controversy that has so enthralled the public intellectuals of our age. The popularity of the question can probably be traced to Western unease with a rising China and the ease with which the issue can be used as proxy war for the much larger contest between Western liberals who embrace multiculturalism and conservatives who champion the West’s ‘unique’ heritage.
A few months ago I suggested that many of these debates that surround the “Great Divergence” are based on a flawed premise–or rather, a flawed question. As I wrote:
“Rather than focus on why Europe diverged from the rest in 1800 we should be asking why the North Sea diverged from the rest in 1000.” 
I made this judgement based off of data from Angus Maddison‘s Contours of the World Economy, 1-2030 AD and the subsequent updates to Mr. Maddison’s data set by the scholars who contribute to the Maddison Project.
As far as 1,000 year economic projections go this data was pretty good. But it was not perfect. In many cases–especially with the Chinese data–it was simply based on estimates and extrapolations from other eras. A more accurate view of the past would require further research.
That research has now been done. The economic historian Stephen Broadberry explains:
As it turns out, medieval and early modern European and Asian nations were much more literate and numerate than is often thought. They left behind a wealth of data in documents such as government accounts, customs accounts, poll tax returns, Parish registers, city records, trading company records, hospital and educational establishment records, manorial accounts, probate inventories, farm accounts, tithe files. With a national accounting framework and careful cross-checking, it is possible to reconstruct population and GDP back to the medieval period. The picture that emerges is of reversals of fortune within both Europe and Asia, as well as between the two continents. 
Drawing on a multiple specialized studies, Mr. Broadberry is able to create a table that is more accurate than the one I used earlier:
|Taken from Stephen Broadberry. “Accounting for the Great Divergence.” voxEU.org. 16 November 2013.
There are a few things here worth commenting on.