Date of Birth: unknown.
Place of Birth: unknown.
Bartrum given Tangwystl a number of 5 in his generational dating system, which implies a birth date of, very roughly, about 1170.
Date of Death: unknown.
Place of Death: unknown.
Relationships
Father: Llywarch Gȏch ab Iorwerth ap Cynon.
This relationship is shown by Bartrum (Llywarch Howlbrwch 1). Bartrum cites a land transaction in which Tangwystl sold land given her by Llywelyn Fawr to her presumed brother, Cynon ap Llywarch.
Mother: Tangwystl ferch Llywarch ab Brȃn.
This relationship is shown by Bartrum (Llywarch Howlbrwch 1).
Relationship outside of marriage: Llywelyn Fawr ab Iorwerth Drwyndwn ab Owain Gwynedd.
This relationship is shown by Bartrum (Gruffudd ap Cynan 4; Llywarch Howlbrwch 1) and given by Carr (ODNB).
Children:
(Complete source citations for facts about the children on this page are currently outside of the scope of this project. The information below comes from Bartrum.)
Gruffudd (died 1244) married (1) Senena ferch Caradog; possibly married (2) Rhanullt, daughter of Ragnvald Godredsson; married (3) Catrin ferch Cynchwr of Ireland.
Gwenllian (died 1291) married William de Lacy.
References
Bartrum, Peter C., “Llywarch Howlbrwch 1” in An Electronic Version of Welsh Genealogies AD 300-1500. [The sources Bartrum cites for Tangwystl are: Peniarth 129 (124), copied about 1500 from a 1497 MS by Gutun Owain; Peniarth 128 (760a), “Llyfr Edward ap Roger”, written before 1582; and Peniarth 134 (62, 302) by Gruffudd Hiraethog (died 1564)]
Carr, A.D. “Llywelyn ab Iorwerth (c. 1173-1240)”, in the Oxford Dictionary of National Biography. (Oxford University Press, 2004).