Question: when did the ring became a symbol of marriage
[{'answer': '6,000 years ago ,', 'provenance': [{'wikipedia_id': '163668', 'title': 'Wedding ring', 'start_paragraph_id': 5, 'start_character': 111, 'end_paragraph_id': 5, 'end_character': 137, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '163668', 'title': 'Wedding ring', 'start_paragraph_id': 5, 'start_character': 0, 'end_paragraph_id': 5, 'end_character': 628, 'bleu_score': 0.9815648442794911, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11710968733459995812}, 'section': 'Section::::History.\n'}]}]