Question: when was thaba nchu established as a settlement
[{'answer': '1873', 'provenance': [{'wikipedia_id': '4761221', 'title': "Thaba 'Nchu", 'start_paragraph_id': 1, 'start_character': 234, 'end_paragraph_id': 1, 'end_character': 238, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '4761221', 'title': "Thaba 'Nchu", 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 434, 'bleu_score': 0.928680631194693, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3294943691162202598}, 'section': 'Section::::Abstract.'}]}]