How did Bede help spread the use of BC and AD dating?

While the Christian Era dating system was originally invented by Dionysius Exiguus in the 6th century, it was St. Bede the Venerable who played a pivotal role in its widespread adoption and popularization during the 8th century.123

Bede helped spread this system through several key methods:

• Historical Writing: His influential work, Historia ecclesiastica gentis Anglorum, utilized the anno Domini (AD) dating system, which helped normalize its use among readers and scholars across Europe.12
• Chronological Treatises: Bede authored two significant works on chronology, De temporibus and De temporum ratione, which provided the mathematical and historical framework for reckoning time from the Incarnation.1
• Marginal Annotations: He famously used the margins of Easter tables to record historical events, effectively juxtaposing historical narratives with calendrical computations. This practice demonstrated the utility of the system for organizing history.2
• Educational Influence: Bede’s methods were transmitted to the rest of Europe through his pupils, such as Archbishop Egbert of York, and subsequently through Alcuin, who served as master of Charlemagne’s palace school.1

Bede also explicitly referenced the period before the Incarnation, laying the groundwork for what would later become the "before Christ" (BC) designation.3