We have very little information about Llywarch's life apart from the evidence of his poetry. He was most probably from the commote of Is Dulas (the eastern part of the cantref of Rhos, near Llandulas in the Perfeddwlad). In 1334, the survey of the Lordship of Denbigh recorded the gwely (in this case meaning tribal land) of Prydydd y Moch.4 The poet may have acquired this land by the patronage of Llywelyn. Also recorded is a "mill of Prydydd y Moch", and the poet may have had significant earnings from grinding the corn of local farmers.5
His pseudonym Prydydd y Moch can be interpreted in various ways. It might refer to some defiant poetic lines threatening Gruffudd ap Cynan ab Owain Gwynedd, comparing singing to that prince with "casting pearls before swine" (Gospel of Matthew, chapter 7). Another possibility is that the poet was a swineherd, before attaining bardic status in his youth.
Nineteen of his awdlau are extant (a total of 1,318 lines), together with 11 series of englynion (462 lines). This body of poetry is second only to the work of Cynddelw Brydydd Mawr. His works celebrate several princes and lords of Gwynedd, as well as princes of Powys, Arwystli, and the Deheubarth. His only known works to sing praise to someone other than his sponsors are his awdl to Gwenllïan ferch Hywel from the cantref of Gwynllŵg, and the 'Awdl yr Haearn Twym' ("awdl of the warm iron").6
Llywarch was the court poet for the House of Aberffraw on the isle of Anglesey, and working for Dafydd ab Owain Gwynedd, and for Llywelyn the Great he became chief poet; he wrote nine poems for Llywelyn. The poem Poetry to God is attested to him in the Hendregadredd Manuscript, however both the Red Book of Hergest and The Myvyrian Archaiology of Wales attribute the poem to Cynddelw.7
(Lloyd 1959) - Lloyd, David Myrddin (1959). "LLYWARCH ap LLYWELYN ('Prydydd y Moch '; fl. 1173–1220); the most prominent court-poet of Gwynedd". Dictionary of Welsh Biography. National Library of Wales. https://biography.wales/article/s-LLYW-APL-1173 ↩
(Jones 1991) - Jones, Elin M.; Jones, Nerys Ann (9 May 1991). Gwaith Llywarch Ap Llywelyn "Prydydd y Moch" [The work of Llywarch ap Llywelyn, 'Poet of the Pigs']. University of Wales Press. ISBN 9780708310847. ↩
"Dictionary search enging". welsh-dictionary.ac.uk. https://welsh-dictionary.ac.uk/gpc/gpc.html ↩