Question: when did the huns invade the roman empire
[{'answer': '447', 'provenance': [{'wikipedia_id': '13519', 'title': 'Huns', 'start_paragraph_id': 25, 'start_character': 3, 'end_paragraph_id': 25, 'end_character': 6, 'bleu_score': 1.0, 'section': 'Section::::History.:Under Attila.\n'}]}]