Nielsen Hayden genealogy
Descendants of Gwladus ferch Llywarch
Father: Llywarch ap Trahearn ( - Aft 1124)
Gwladus ferch Llywarch
Owain Gwynedd, King of Gwynedd ( - 1169 bur.Bangor Cathedral, Bangor, Gwynedd, Wales)
   ├─ Iorwerth Drwyndwn ap Owain Gwynedd ( - Abt 1174)
   │ Margred ferch Madog
   │    └─ Llywelyn Fawr ap Iorwerth (Abt 1173 - 11 Apr 1240 Aberconwy Abbey, Conwy, Wales)
   │     (One of the several mistresses of Llywelyn ap Iorwerth)
   │     :   │ + John de Brewes (Abt 1197 of Gower, Swansea, Wales - Between 1231 and 1232)(m. 1219)
   │     :   │ + Walter IV de Clifford (of Clifford, Herefordshire, England - Bef 23 Dec 1263)(m. Bef 2 Nov 1234)
   │     :   │ + Donald of Mar ( - Aft 25 Jul 1297)
   │     :   └─ Tegwared y Baiswen ap Llywelyn ab Iorwerth Drwyndwn ab Owain Gwybnedd (Abt 1200 - ??) =>
   │     :    + Gwenllian ferch Ednyfed Fychan
   │     Tangwystl
   │     :   └─ Grufudd ap Llywelyn ab Iorwerth Drwyndwn ab Owain Gwybnedd ( - 1 Mar 1244 Tower of London,
   │     :    London, England) =>
   │     :    London, England) =>
   │     :    + Senena ferch Caradog
   │     Joan of England (Bef 1190 - 30 Mar 1236 bur.Llanvaes, Anglesey, Wales)(m. Bef 23 Mar 1205)
   │     :   ├─ Gwladus Ddu ( - 1251 Windsor, Berkshire, England) =>
   │     :   │ + Reynold de Briouze (of Abergavenny, Monmouthshire, Wales - Between 1227 and 1228)(m. 1215)
   │     :   │ + Ralph de Mortimer (of Wigmore, Herefordshire, England -
   │     :   │ 6 Aug 1246 bur.Wigmore Abbey, Herefordshire, England)(m. Bef 26 Oct 1230)
   │     :   │ 6 Aug 1246 bur.Wigmore Abbey, Herefordshire, England)(m. Bef 26 Oct 1230)
   │     :    + Robert de Quincy (Bef 1200 of Wakes Colne, Essex, England - Aug 1257)(m. Bef 5 Dec 1237)
   │     + Eve Fitzwarine ( - Aft 1281)(m. 1239)
   └─ Gwenllian ferch Owain
    Owain Cyfeiliog ap Gruffudd ap Maredudd ap Bleddyn ap Cynfyn (Abt 1130 -
    1197 Monastery of Strata Marcella, Welshpool, Montgomeryshire, Wales)
    1197 Monastery of Strata Marcella, Welshpool, Montgomeryshire, Wales)
       ├─ Gwenwynwyn ( - Abt 1216 Cheshire, England)
       │ Margaret Corbet
       │     + Hawise le Strange ( - 1310)(m. Bef 1242)
       └─ Constance ferch Owain
        David de Malpas
           └─ Idonea de Malpas ( - Bef 1295 Malpas, Cheshire, England) =>
            + Urian de St. Pierre (1220 - Between 1290 and 1300 Cheshire, England)