Between 400 and 450 Christianity was established in the area by St Ninian, a bishop and a Briton, whose main church was at Whithorn in the Machars.
An almost equally early site is at Kirkmadrine in the Rhins where three early monumental stones commemorate three priests or bishops.

Between 500 and 700 many churches dedicated to Irish saints were established, at Killumpha, for example, 'church of Iomchadh' (a very obscure saint), at Killasser 'church of Lasair,' a woman saint, and at Kildonan, 'church of Donnan', martyred on the island of Eigg in 618. Kirkmaiden, 'church of my Etain (Medana),' Kirkbride, 'Brigid's church' (i.e., St Brigid of Kildare), and Kirkmabreck, 'church of [Aedh] mac Bricc,' an Irish bishop, are later in form, but their origins go back to the same early period.

Holy wells came under the patronage of other Irish saints. Chipperdingan, 'well of your Finnian,' is an example. The saint is probably Finnian of Moville (c.475-579), the chief patron of Ulster.