Question: when did we start using bc and ad
[{'answer': 'the late eighth century', 'provenance': [{'wikipedia_id': '1400', 'title': 'Anno Domini', 'start_paragraph_id': 17, 'start_character': 153, 'end_paragraph_id': 17, 'end_character': 176, 'bleu_score': 1.0, 'section': 'Section::::History.:Popularization.\n'}]}, {'provenance': [{'wikipedia_id': '1400', 'title': 'Anno Domini', 'start_paragraph_id': 17, 'start_character': 0, 'end_paragraph_id': 17, 'end_character': 871, 'bleu_score': 0.9860618656782161, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6690940062012383172}, 'section': 'Section::::History.:Popularization.\n'}]}]