Is there a study of world poverty rates over time pre 1800? There seems to be research showing that world poverty rates have declined since 1800, see eg this. Is there any research on world poverty rates before this period? I am guessing that during this period poverty in much of the world would have gone up as a result of European colonisation.
This is only for Europe unfortunately, but Bob Allen has a famous paper in which he presents reconstructed data for real wages in different European cities from 1350 all the way to 1799:


  Allen, Robert C. "The great divergence in European wages and prices from the Middle Ages to the First World War." Explorations in economic history 38.4 (2001): 411-447.


From real wages and price data, he then infers a measure of (extreme) poverty.

Look at Figure 5 in the paper. The scale of the y-axis is a measure of poverty in which 1 is the poverty threshold. Values above 1 on the y-axis correspond to real wages lower than survival rate (i.e. that do not allow a survival caloric intake), and values above 1 indicate a real wage above survival rate.