Traditionally established in sub-apostolic times, the diocese as metropolis of Quarta Lugdunensis subsequently achieved metropolitical status.

[1] The history of the religious beginnings of the church at Sens dates from Savinian and Potentian, and through legend to the Dioceses of Chartres, Troyes and Orléans.

Gregory of Tours is silent regarding Savinian and Potentian, founders of the See of Sens; the Hieronymian Martyrology, which was revised before 600 at Auxerre (or Autun) ignores them.

In 847, the transfer of their remains to the church of St-Pierre le Vif inspired popular devotion towards Savinian and Potentian.

In the middle of the 10th century the relics of these two saints were hidden in a subterranean vault of the Abbey of St-Pierre le Vif to escape the pillage of the Hungarians, but in 1031 they were placed in a reliquary established by the monk Odoranne.

This monk (in a chronicle published about 1045) speaks of Altinus, Eodaldus, and Serotinus as apostolic companions of Savinian and Potentian, but does not view them as legitimate.

In a document which (according to the Abbé Bouvier) dates from the end of the sixth century or the beginning of the seventh—but according to Louis Duchesne, who labels the Gerbertine legend as written in 1046 and 1079 under the inspiration of Gerbert, Abbot of St-Pierre le Vif—is first described a legend tracing to Savinian and Potentian (and their companions) the evangelization of the churches of Orléans, Chartres and Troyes.

The see regained some prestige when Hugues de Toucy (1142–1168) crowned Constance (wife of King Louis VII) at Orléans in 1152 despite protests by the Archbishop of Reims, and during whose episcopate Pope Alexander III (driven from Rome) installed the pontifical court at Sens for 18 months, on the advice of the bishops.