DDU OF TAL-Y-LLYN
By Darrell Wolcott
Bartrum  charts a single Rhydderch Ddu but claims the sources give him two different ancestries. On his chart "Drymbenog
1", he makes him "ap Dafydd ap Cadwgan ap Drymbenog ap Maenrych" and alternately, "ap Cadwgan Fawr ap Bleddyn ap Rhiwallon
Rwth ". He originally dated him to his Generation 5 (c. 1170) on this chart, but labels the same man as Generation 4
in his index of names. He subsequently corrected the chart to show Generation 4 for Rhydderch Ddu, and moved his predecessors,
back to Rhiwallon Rwth at Generation 1, respectively, but he did nothing with the line leading back to Drymbenog, still holding
to a single man named Rhydderch Ddu.
He also dates him to his Generation 4 in his chart "Rhydderch Ddu 1". On the latter chart, he dates a son, Owain, to Generation
5 and attaches four sons to Owain. Two of those sons he dates to Generation 6 and the other two to Generation 7.
Bartrum matches his Generation 4 Rhydderch Ddu with wife, Lleuci (1145) ferch Cadwgan (1110) ap Rhys (1075) ap Morda Frych
(1040)  and his Generation 5 Owain with wife Mawd (1165) ferch Aaron (1130) ap Rhys (1095)
ap Bledri (1065) ap Cadifor Fawr (1030). He admits, however, that his sources called the lady Mawd ferch Aaron ap Bledri.
 After reviewing the entire Cadifor Fawr pedigree, we chart these two marriages as:
Cadifor Fawr 1030
Morda Frych Drymbenog 1050 Bledri 1065
1075 Rhys Cadwgan 1085
1110 Cadwgan Dafydd 1115
1145 Lleuci======Rhydderch Ddu 1145 Aaron 1160
1180 Owain =================Mawd 1195
While it is unlikely that the charted Lleuci was
the mother of Owain, she could have been a later-in-life consort of Rhydderch Ddu, who was clearly born in Bartrum's Generation
RHYDDERCH DDU #2
The alternate ancestry charted by Bartrum belongs to a wholly different man named Rhydderch Ddu. But he cannot be dated
by his assigned ancestry. Bartrum points us to a series of pedigrees  which place his ancestor, Rhiwallon Rwth, as
a brother to the c. 980 Dryffin, who was grandfather of King Bleddyn ap Maenyrch. However, none of those pedigrees are
chronologically stable even when modified as Bartrum suggests. 
Even with Bartrum's chart correction dating Rhiwallon Rwth to his Generation 1, he is left with a Rhiwallon Rwth that falls
over a generation earlier than he should, and a Rhydderch Ddu who falls in Generation 4 for one of his lines, and Generation
5, for the other line. It is necessary to examine those folks who descended from Rhydderch Ddu (other than those already
identified as belonging to Rhydderch Ddu #1) in order to date this other same-named man.
In our first chart above, we show an Owain (Generation 5) as a son of Rhydderch Ddu (Generation 4). This Owain should
be the father of sons Arod and Owain Fychan since those men are dated Generation 6. We shall begin our analysis, then,
with Richard of Generation 7 as a likely grandson of a different Rhydderch Ddu, one born in Generation 5:
1100 Gwaithfoed of Meirionydd
Cadwgan Fawr Hoedliw 1140 Cadifor
Rhydderch Ddu Llewelyn 1170 Iorwerth
1205 Owain Rhys 1205
1235 Richard Richard 1240
Gruffudd Foel 1230
1265 Dafydd Hywel 1270
1295 Hywel Ieuan 1300
Ieuan Llwyd 1295
1330 Ieuan=========daughter  1335 Dafydd 1325
Elen==================Ieuan  1355
These marriages place Rhiwallon Rwth in Bartrum's Generation 2 and in the same generation as sons of King Bleddyn, Drymbenog,
Rhiwallon and Dryffin ap Maenyrch. It is thus possible that Rhiwallon Rwth was a son of one of those brothers.
However, none of the 9 citations which mention him also name his father.  Since Bartrum mishandled the entire family
which descended from Dryffin ap Maenyrch ap Dryffin, we elected to chart Rhiwallon Rwth as a son of that Dryffin ap Maenyrch.
The other son of Owain ap Rhydderch Ddu whom Bartrum dates to his Generation 7 was Rhys ap Owain. In analyzing the family
of this Rhys, we found Brycheiniog families who descended from Eidio Wyllt  which made marriage matches with families descended
from both of the men named Rhydderch Ddu:
This chart shows a same-named string of men descended from both men named Rhydderch Ddu. The string actually extends
a generation further since the Einion Cest of c. 1305 also had a son named Madog but nicknamed Sais.  Three other
children charted by Bartrum for Einion Cest also belong to this later Einion Cest. 
FYCHAN AP LLEWELYN:
In reviewing the descendants of Rhys ap Owain ap Rhydderch Ddu, we found one other major error on the Bartrum chart "Rhydderch
Ddu 6". In the column found at the far left of this Bartrum chart, Hywel Fychan was NOT a son of either Llewelyn ap
Rhys ap Owain which appear in our chart. There was one more same-named string of men in this family:
1145 Rhydderch Ddu
(no son named Hywel Fychan) 1270
1370 Hywel Fychan
Nest (1430) ferch Ieuan Ddu married Iorwerth (1415) ap Gruffudd Llwyd (1380) ap Iorwerth (1350) ap Gruffudd Fychan (1320)
ap Dafydd Fongam (1280) ap Dafydd (1250) ap Meurig Goch (1220) ap Gruffudd (1185) ap Cadifor (1155) ap Selyf (1125) ap Cadifor
(1090) ap Selyf (1055) of Dyfed. 
OF RHYDDERCH DDU:
The earliest citation to assign a residence location to Rhydderch Ddu was Peniarth Ms 131, 222, penned by Ieuan Brechfa about
the year 1500. Brechfa said that Rhydderch Ddu #2, the one whose father was Cadwgan Fawr, resided in the parish of Tal-y-llyn.
That parish was in the commote of Talgarth in the northern part of the cantref of Talgarth in the kingdom of Brycheiniog.
About 100 years later, Lewis Dwnn (vol i, 205) penned a pedigree of Rhydderch Ddu #1, whose father was named Dafydd, which
placed that Rhydderch Ddu at Bwlch yr arllwys, a manor in the commote of Ystrad Yw in the southern part of the cantref of
Talgarth. While this manor may have been as close as 1 mile to as much as 12 miles from a manor in Tal-y-llyn, an exact
location cannot be determined for either man's residence. Dwnn actually drew from Brechfa, assigning his Rhydderch Ddu
to both Tal-y-llyn and Bwlch yr arllwys.
The fact that both men named Rhydderch Ddu began a 200 year string of same named sons, indicates the families remained in
close contact for an extended period and likely did not live very far apart.
Peter Bartrum "Welsh Genealogies AD 300 - 1400", 8 volumes, 1974, University of Wales Press
Harl. 1975, 46 and Harl. 5835, 46 cite this marriage
Harl. 1975, 60 and Harl. 5835, 47 cite the marriage, calling her Mawd ferch Aron ap Bledri.
See pedigree #15 - Maenyrch, pedigrees (3) and (4) and sources labeled "B" in both, in "Pedigrees of the Welsh Tribal Patriarchs"
published in Vol XII number 2, The National Library of Wales Journal, 1963
See our paper on Welshmen Named Maenyrch at the link below:
 Protheroe IV, 193 cites this marriage
 Pen. 131, 243 cites this marriage
 Pen. 132, 125; Pen. 132, 126;Pen. 136, 350; Pen. 140, 135;
Mostyn 114, 4; Pen. 131,263; Pen 140, 136; Pen. 133, 115; Pen. 131,222
 See our paper on Eidio Wyllt at the following link:
 Protheroe IV. 194 cites "Thomas ap Madog Sais ap Einion Cest"
 These were Gwilym, Marged and the aforementioned Tangwystl, all born c. 1335/40 and
children of the c. 1305 Einion Cest
 The charted marriage is cited in Pen. 131, 228