A number of ascetics chose the tops of hills. One such was the hermit
and monastic founder St Gwyddfarch. We know little about his early life
beyond the fact that he was part of the community founded by his
spiritual father, St Llywelyn at Trallwng (Tre = town, Llwng = Llywelyn,
i.e. Llywelyn's Town), now know in English as Welshpool. This was at
some point during the sixth century. It was part of the "Eastern
Mission" i.e. the influx of Christian Britons into Wales from what is
now Shropshire and probably in particular from the town of Wroxeter
(Uriconium).
From Trallwng Gwyddfarch set out into rather wilder country to the North
East and settled in the Vyrnwy Valley near to the present-day village of
Meifod. Above this valley is a solitary, steep-sided hill and it was
close to the summit of this that Gwyddfarch built his cell, lived and
finally died. It was here that he was buried and he is still there to
this day. The hill is now known as Moel yr Ancr (the bald hill of the
anchorite). Looking at the setting today it is astonishingly beautiful
and pastoral and shows little signs of being a desert. In winter,
however, when there is a cold East wind one can better appreciate that
living on the top of that hill surrounded by wolf-infested woods was
hard, cold and uncomfortable - not so far off the deserts of North
Africa! St Gwyddfarch is commemorated on November 3rd.
The above is from "The Deserts of Britain"
by Fr Stephen Maxfield
https://web.archive.org/web/20031020184544/http://www.nireland.com/orthodox/deserts.htm
Additional information from "History of the Church of the Holy Fathers"
by Fr Stephen Maxfield
https://web.archive.org/web/20061012225835/http://www.shorthodox.freeserve.co.uk/History.htm
...With the withdrawal of the legions at the beginning of the fifth
century a period of considerable political instability followed.
However Viroconium continued to flourish for some time. For instance St
Germanus of Auxerre came to Britain to counter
the teachings of the heresiarch Pelagius in 429 and again in 447. He
certainly visited Viroconium, indeed it seems to have been the base for
his mission into what is now mid and north Wales: The last British
Archbishop of London, Theonas (Teon) fled to Viroconium in 586 when
London fell to the pagan Saxons. The range of hills known now as the
Stiperstones are called, in Welsh, Carneddi Teon in memory of him. Some
of Teon's disciples, including his grandson St Llywelyn, started a
monastery at Welshpool, and their mission helped convert mid Wales
particularly through the work of their disciples Sts Gwyddfarch and
Tysilio.
St. Tysilio (born c.548-640) (Latin-Disilius, English-Tysilio) was
Prince Tyslio (or Sulio) was the second son of Brochfael Ysgythrog (of
the Tusks). He fled his father's court at an early age to throw himself
on the mercy of Abbot Gwyddfarch of Caer-Meguaidd (Meifod) and beg to
become a monk.
Caer-Meguaidd may be Meifod, the court of the Kings of Powys at the
Manor of Mathrafal from around 750 or before. The place was also a major
ecclesiastical centre. St. Gwyddfarch built the original church which was
replaced by St. Tyslio in about 625. <Nennius, 28 British Cities>