So at school in Northern Ireland I've learnt Irish republican history. Figures such as Eamon De Valera and Michael Collins were emphasised and their legacy was stated. But the founder of Sinn Fein and a figure which seems to me to be just as significant as them if not even more so was seemingly ignored by my teacher. After cursory reading it seems like he was generally airbrushed from history in favour of those other more 'notable' figures. I would like to ask, why was he side-lined? What made Eamon De Valera, Michael Collins or other Irish republican figures more significant in history than Arthur Griffith?
I would very much disagree that Griffith was generally airbrushed from history. He is listed as a “key personality” in the Irish Leaving Certificate curriculum which means he must be taught in the south (If you do a topic search on him in Irish History Online (a useful bibliography at the Royal Irish Academy) it shows a wide range of biographies and articles. An essay on him by Seán O'Lúing was included in the 1968 collection Leaders and men of the 1916 Rising which was probably the most important work in establishing a canon of nationalist history after 1966. Carlton Younger’s biography of him was included in the Gill Irish Lives series which were popular best sellers in the early 1980s. Michael Laffan wrote a hugely important study of early Sinn Féin in 1999. Work on Griffith had continued to appear including that by Owen McGee and Column Kenny. He has always been part of both the official history promoted by the state and the establishment as well as a subject of academic research.
I can only speculate as to why your teacher neglected him. Griffith's views make him awkward for some republicans. He initially advocated a dual monarchy rather than a republic, he wasn’t involved in the 1916 Rising and he was a signatory to and supporter of the Treaty. He was also a journalist rather than a man of violence which made him less glamorous. Arguably his biggest influence was on economic policy where his advocacy of protectionism became SF and later Fianna Fáil policy.
Sources: Irish Leaving Certificate History Curriculum https://www.curriculumonline.ie/getmedia/da556505-f5fb-4921-869f-e0983fd80e50/SCSEC20_History_syllabus_eng.pdf
Irish History Online https://catalogues.ria.ie/Presto/search/SearchResults.aspx?q=KEFydGh1ciBHcmlmZml0aCk=&qcf=NjY3NGZmNzQtY2IwYi00MWU0LWIwYWYtY2MxNzA5NTk4YWVi
Dictionary of Irish Biography https://dib.cambridge.org/viewReadPage.do?articleId=a3644
Michael Laffan, The resurrection of Ireland: the Sinn Féin party, 1916–1923 (1999) F. X. Martin (ed), Leaders and Men of the 1916 Rising (1968) Carlton Younger Arthur Griffith (1981)
[edited to add date for Laffan's book]