In this short podcast, recent BSc in Economic History with Economics graduate Ojonugwa Okeme reviews the various ways in which states set high barriers of exit on all or specific groups of individuals.  These barriers could be political, physical, cultural, religious, or financial, and were used to control the influx or exit of wealth, labour and skilled craftsmen, or groups deemed desirable or undesirable to the body politic. 

You can listen to the podcast via this link:  The relationship between barriers of exit and state formation