Question: an empire in west africa that became a powerful state
[{'answer': 'Ghana Empire ( Wagadu )'}, {'provenance': [{'wikipedia_id': '14762552', 'title': 'African empires', 'start_paragraph_id': 5, 'start_character': 0, 'end_paragraph_id': 5, 'end_character': 525, 'bleu_score': 0.978606533029418, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 519121585102075448}, 'section': 'Section::::Sahelian kingdoms.\n'}]}]