Holt was the per-eminent historian of the Sudan. His first book,
The Mahdist State in the Sudan 1881–1898. A Study of its Origins, Development, and Overthrow (1958) was based on his DPhil thesis, and was followed by
A modern history of the Sudan, from the Funj Sultanate to the present day (1965, later republished as
The history of the Sudan from the coming of Islam to the present day). He then expanded his interests geographically, publishing
Egypt and the Fertile Crescent 1516-1922, A Political History in 1966). He then added a second field, becoming an authority on the
Mamluk Sultanate, (1250-1517), publishing ''The memoirs of a Syrian prince: Abu'l-Fidā, Sultan of Ḥamāh (672-732)
(1983) and Early Mamluk diplomacy (1260 - 1290): Treaties of Baybars and Qalāwūn with Christian rulers
(1995). A general history of the Near East, The Age of the Crusades, The Near East from the Eleventh Century to 1517'' was published in 1986. Holt was also one of the founding editors of
The Cambridge History of Islam, along with
Ann K. S. Lambton and
Bernard Lewis. His work on Sudan was carried forward by one of his PhD students,
Seán O'Fahey. == Works ==