Question: when were the motte and bailey castles built
[{'answer': '10th century onwards', 'provenance': [{'wikipedia_id': '373601', 'title': 'Motte-and-bailey castle', 'start_paragraph_id': 1, 'start_character': 369, 'end_paragraph_id': 1, 'end_character': 389, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '373601', 'title': 'Motte-and-bailey castle', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 865, 'bleu_score': 0.9855586187885531, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9183947384679550620}, 'section': 'Section::::Abstract.'}]}]