Pam Wilson (on hiatus) -- I'll add notes on Welsh sources here.
MEDIEVAL WELSH GENEALOGY
We have a great many medieval, or copies of medieval, manuscripts that give Welsh genealogies. Some have been microfilmed; some have not. They are held in such repositories as The National Library of Wales, the College of Arms, and the British Library, as well as being scattered around in various other archives.
These are of course inaccessible, unless you travel to the archives.
There are many transcriptions, though.
The problem is that the manuscripts contradict each other.
This means that you can blithely follow a pedigree, and discover that it doesn't fit at all into the collection of people gathered onto some place like, oh, for instance, Geni.
One of the most easily accessible sources, for instance, is ''Heraldic Visitations of Wales and Part of the Marches Between the Years 1586 and 1613 by Lewys Dwnn'' (1846), Dwnn, Lewys; transcribed and edited with notes by Sir Samuel Rush Meyrick, (2 volumes. Llandovery: William Rees, 1846), https://archive.org/details/HeraldicVisitationsOfWalesAndPartOfTheM...
BUT IT IS HIGHLY PROBLEMATIC. So don't be surprised when you discover that a pedigree on one page is contradicted by a pedigree on the next.
LUCKILY THERE IS HELP
In the 20th century, Peter Bartrum, an English researcher and genealogist who learned Welsh specifically so that he could work with the Welsh manuscripts, published The Welsh Genealogies (this takes three parts, in several volumes -- Early Welsh Genealogical Tracts (1966); Welsh Genealogies AD 300-1400 (1974); Welsh Genealogies AD 1400-1500 (1983)) -- and this is the gold standard in medieval Welsh genealogy.
What he did was to collate the medieval manuscripts, and work out the contradictions. His work includes reference to the manuscripts he used. It is a secondary source, but it is highly reliable, highly respected, and, in such a case, wherein the primary sources are so problematic and contradictory, it is a great gift to us all.
HOWEVER THERE IS ANOTHER PROBLEM
Alas, these volumes are out of print. And if you can find them, they are extraordinarily expensive. You may be able to find them in one of your local libraries. But it's unlikely that any of us have them on our shelves. I don't.
BUT GUESS WHAT THERE IS SOME HELP FOR THIS TOO! ONLY SORT OF ALSO PROBLEMATIC!
Luckily, the University of Aberystwyth has uploaded most of Bartrum's notes -- not the published work, no, but his handwritten pedigrees -- onto the Cadair server.
Yay.
Alas, the Cadair server is unavailable pretty often -- I find it's catch as catch can.
Nevertheless!
I've had a project for three years now; I'm putting the Welsh Genealogies into Geni, with links to Bartrum's notes. So, on the days when Cadair is up, you can actually see Bartrum's handwritten notes.
As for instance -- if you go and visit the profile for Owain Glyndwr ap Gruffudd, Prince of Wales you can see that in the Overview there is a link to the Bartrum pedigree page (sometimes there are several pages for one profile) that included Owain Glyndwr, and if you click on that link, and it's a good day, you can see the pedigree! And if you need help deciphering it, you just message me. No prob.
IS THAT THE END OF THE PROBLEMS? NO! NO, THERE ARE MORE!
Earlier this year, Cadair overhauled the server, or something like that, and it was down for about a month, which made me pretty darn depressed, let me tell you, but then it came back up again, at which point none of the links -- that I had been entering for three years -- would work.
It turns out that this is fixable -- the web address that I had used earlier started out "http," and it needs to be changed, simply, to "https."
Great.
So I'm changing the old addresses as I come across them. If you click on one of my links and it takes you not to a pedigree page but to the Cadair index, the problem is that the address needs to be updated.
Great.
FURTHER HELP! BECAUSE WHY NOT!
So, in essence, Bartrum is the gold standard and we are all grateful for his work.
He did not iron out ALL of the problems with the manuscripts, though.
To that end, Darrell Wolcott has been working with the manuscripts, historical documents, and land documents to work out some of the problems left by Bartrum's work.
As Private User mentions above, Wolcott is one of the important workers in the field -- you can find him at http://www.ancientwalesstudies.org/ -- much of the site is work in progress, but it is extremely useful.
In the same way as I have been entering Bartrum's information into Geni, Steven Mitchell Ferry has been entering Wolcott's work into Geni -- as I do, he puts links into the Overviews of profiles, and you can often see both of us adding Bartrum and Wolcott to a profile, as in this one -- Tangwre verch Gwyn II
That is the News From the Welsh Medieval Geni Thicket.
Do stop by to visit.
But please be very very very careful.
It's a very thorny thicket.
