Question: where were the celts said to have migrated from
[{'answer': 'Central Europe', 'provenance': [{'wikipedia_id': '6546', 'title': 'Celts', 'start_paragraph_id': 1, 'start_character': 709, 'end_paragraph_id': 1, 'end_character': 723, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '6546', 'title': 'Celts', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 874, 'bleu_score': 0.574018894967818, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14790150576776241095}, 'section': 'Section::::Abstract.'}]}]