Where can I find data on income and social mobility over time? How far back is data available? I'm interested in income and social mobility. I understand that Piketty's research deals with the the distribution of income over a long time period. I have also seen some of Chetty and Saez's research concerning income and social mobility in the US. I'm wondering, what data do Chetty and Saez work use? What other data is potentially available and how far back does it go?

It would be nice to see who could find the data that goes back the farthest. (Also, the data does not necessarily have to be US data.)
Maybe check Clark's work. He allegedly uses long time series.
http://jasoncollins.org/2014/09/30/the-genetic-basis-of-social-mobility/