Question: . in 1219 which mongol king attacked trans oxania
[{'answer': 'Genghis Khan', 'provenance': [{'wikipedia_id': '23540084', 'title': 'Mongol conquest of Khwarezmia', 'start_paragraph_id': 2, 'start_character': 134, 'end_paragraph_id': 2, 'end_character': 146, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '23540084', 'title': 'Mongol conquest of Khwarezmia', 'start_paragraph_id': 18, 'start_character': 0, 'end_paragraph_id': 18, 'end_character': 588, 'bleu_score': 0.979054689945215, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13940750244897063064}, 'section': 'Section::::Planning and dispositions.:Forces.\n'}]}]