In 1990 he came back to Burma and worked as a Member of the Myanmar (Burmese) Historical Commission and Emeritus Professor in University of Yangon in the Departments of History and Archeology.
In this study, he compared the existing copies of royal orders from the dynasty period and subjected them to rigorous analysis.
This voluminous work of 7,600 pages includes an abridged English translation, commentaries, and index, and is the most reliable collection of original historical documents.
Professor Than Tun was very critical of the military junta’s defacing of the ancient Burmese capital the Old Bagan with unnecessary, garish and over-the-top ‘re-innovations’ of its ancient temples, the construction of a motorway among the ruins and the erection of an observation tower for the benefits of dollar yielding tourists.
The professor was buried in a cemetery on the outskirts of Amarapura, south of Mandalay, where some 300 people, many of them former students, gathered to mourn his death.