The existence of fief - large farmsteads is one of the outstanding features that contributed to the socio-economic establishment of the Tran Dynasty. This is a glorious period in Vietnamese history with the achievement of three successful victories against the Mongol invasion. In this book, the author has quite clearly reviewed the situation of Dai Viet society in the Tran dynasty in terms of economy, politics, government organization, army ... The author also introduces some new content in the study of the history of the Middle-Medieval period when linking agricultural issues, land and the existence of fiefs with natural and environmental conditions. The author shows the positive meaning of these types of fief in building and defending the country, together with the disadvantages of them, caused dispersal conflict with the centralized trend of that period.