Situated at the junction of the Tamina and Rhine valleys, it flourished as a religious house and owner of lands and serfs, as well as assuming extraordinary importance as a political and cultural centre of the Chur–Raetian region.

The substantial influence of the monastery was concentrated in eastern Switzerland, especially between Weesen and Maienfeld, but reached as far as present-day Baden-Württemberg, in the Val Bregaglia, the Vinschgau and the County of Tyrol.

The East Frankish king Louis the Child gave Pfäfers, in 905, to Solomon III, Bishop of Constance, who was also the abbot of St Gall.

In 1208, Otto IV, Holy Roman Emperor, passed Vogtei (protectorship) of the monastery to the Barony of Sax, to whom the monks pledged at least partial allegiance.

In 1257, Abbot Rudolf bought back their freedom for 300 silver marks and, in 1261, transferred it to the Lords of Wildenberg [de] of Freudenberg Castle.

The monastery was caught in the turmoil of the Swabian War and the Protestant Reformation and the general financial and political difficulties that engulfed the region.

Because of the disastrous financial situation, Abbot Zink was forced to resign in 1676, passing control to the Swiss Congregation of the Benedictine Confederation.

His successor, Abbot Boniface I Tschupp, managed the financial recovery and completed the construction in 1694, with the new abbey church dedicated in the same year.

On 11 November 1798, during the French Revolutionary Wars, the county of Sargans was released by the Confederation and Abbot Benedict Bochsler had to free his subjects in a similar manner.