The annals are mainly a compilation of earlier annals, although there is some original work. They were compiled between 1632 and 1636 in the Donegal monastery of the Franciscan order. The entries for the 12th century and before are sourced from medieval monastic annals. The later entries come from the records of the Irish aristocracy (such as the Annals of Ulster), and the seventeenth century entries are based on personal recollection and observation.

The chief author of the annals was Micheal O’Cleirigh, and he was assisted among others by Peregrine O'Clery, Fergus O'Mulconry and Peregrine O’Duigan. Even though only one of the authors, Mícheál Ó Cléirigh was an actual monk, they became known as 'The Four Friars' or in the original 'Na Ceithre Máistrí'. The Anglicised version of this was 'The Four Masters', a name which then became attached to the annals themselves. The patron of the project was Fearghal Ó Gadhra, a Gaelic lord.

The annals are written in Gaelic. There are several manuscript copies in existence, which are kept in TCD, the RIA, and UCD.

The first substantial English translation (starting at 1171 A.D.) was published by Owen Connellan in 1846. The Connellan translation included the annals from the 11th to the 17th centuries complete, and was the only version to have a four-colour frontispiece and include a large folding map showing the location of families in Ireland. It lay nearly forgotten for over 150 years, but was finally salvaged and republished in the early 21st century. The Connellan translation was followed several years later by a full translation by the historian John O'Donovan.

The Annals are one of the principal Irish language sources for Irish history up to 1616. While many of the early chapters are essentially a list of names and dates, the later chapters, dealing with events of which the authors had first-hand accounts are much more detailed.

The reliability and usefulness of the Annals as a historical source has sometimes been questioned on the grounds that they were limited to accounts of the births, deaths and activities of the Gaelic Irish nobility and often ignore wider social trends or events. Moreover, the Annalists came from a bardic tradition that relied on the traditional Irish upper classes for patronage and are reluctant to criticize them or their actions.

On the other hand, the Annals, as one of the few prose sources in Irish from this period, also provide a valuable insight into 17 century events from an Irish perspective.

Because so much original material has been lost over the centuries, especially in the Four Courts fire of 1922, these annals – and others such as the Annals of Ulster - are vitally important for historians. F J Small, writing as Newriensis in 1876 borrowed heavily from the Four Masters for the earlier part of his account of Newry’s history. 

We wanted to make this introduction before reviewing Small’s historical account in depth.