Traditionally, St Tydecho traveled from Brittany with his sister St Tegfedd. Some accounts include a brother too, though his name is variously given as Samson or Dogmael. A contemporary of St David, St Iltud and St Gildas, Tydecho was active throughout the mid-Cardigan Bay area, particularly Mawddwy.
He would have witnessed the Battle of Camlan, in which the annals tell us Arthur and Medraut (aka Modred) died. His churches triangulate the battlefield.
Tydecho's legends largely involve thwarting local Pagan warrior-kings, as they would attempt to hinder or destroy his Christian mission. When the powerful Maelgwn Gwynedd tried to disturb Tydecho's crop planting, the saint prayed for assistance. The High King was duly stuck fast to the rock upon which he sat.
When the Powys chieftain Cynan abducted Tegfedd, her brother's prayers caused the warlord to be struck blind, until he returned the holy lady and begged for forgiveness.
But these weren't the only stories. A local milkmaid was struggling under her load through the Aran Mountains. She stumbled and dropped her pails, spilling all inside. Tydecho found her sobbing beside the stream. He promptly wrought a miracle by which the waters alongside turned into milk. It's still called the Llaethnant (Milk Stream), and it still runs white.
At one time, multitudes of Christians would visit the places associated with St Tydecho. Modern day pilgrims can still do the same.