Question: when did the byzantine empire start to decline
[{'answer': '1071', 'provenance': [{'wikipedia_id': '7441353', 'title': 'Decline of the Byzantine Empire', 'start_paragraph_id': 13, 'start_character': 16, 'end_paragraph_id': 13, 'end_character': 20, 'bleu_score': 1.0, 'section': 'Section::::Causes of the decline.:Civil wars.\n'}]}]