 Postan was born to a Jewish family in Bendery, in the Bessarabia Governorate of the Russian Empire, and studied at the St Vladimir University in Kiev, leaving Russia in 1919 after the October Revolution and settling in the UK.He held positions at University College London and at the London School of Economics, before being appointed Professor of Economic History at the University of Cambridge, from 1937.He was known as an economic historian of medieval Europe.