She was a
reader in Ancient Indian History at
Kurukshetra University in 1961 and 1962 and held the same position at
Delhi University between 1963 and 1970. Later, she worked as Professor of Ancient Indian History at the
Jawaharlal Nehru University, where she is now Professor Emerita. Thapar's major works are
Aśoka and the Decline of the Mauryas,
Ancient Indian Social History: Some Interpretations,
Recent Perspectives of Early Indian History (editor),
A History of India Volume One, and
Early India: From the Origins to AD 1300. Her historical work portrays the origins of
Hinduism as an evolving interplay between social forces. Her 2004 book on
Somnath examines the evolution of the historiographies about the legendary Gujarat temple. In her first work,
Aśoka and the Decline of the Maurya published in 1961, Thapar situates
Ashoka's policy of
dhamma in its social and political context, as a non-sectarian civic ethic intended to hold together an empire of diverse ethnicities and cultures. She attributes the decline of the
Maurya Empire to its highly centralised administration which called for rulers of exceptional abilities to function well. Thapar's first volume of
A History of India is written for a popular audience and encompasses the period from its early history to the arrival of Europeans in the sixteenth century.
Ancient Indian Social History deals with the period from early times to the end of the first millennium, includes a comparative study of Hindu and Buddhist socio-religious systems, and examines the role of Buddhism in social protest and social mobility in the caste system.
From Lineage to State analyses the formation of states in the middle Ganga valley in the first millennium BCE, tracing the process to a change, driven by the use of iron and plough agriculture, from a pastoral and mobile lineage-based society to one of settled peasant holdings, accumulation and increased urbanisation. ==Views on revisionist historiography==