Complex sentence: The most splendid age of Sant Benet de Bages was in the fourteenth century, until the Black Death left the community with only two survivors, in a period that witnessed the beginning of its decline.
Split into simpler sentences: The most splendid age of Sant Benet de Bages was in the fourteenth century. The Black Death left the community with only two survivors, in a period that witnessed the beginning of its decline.