Question: which group ended the period of kievan rus dominance
[{'answer': 'Mongol invasion', 'provenance': [{'wikipedia_id': '21486360', 'title': "Kievan Rus'", 'start_paragraph_id': 4, 'start_character': 386, 'end_paragraph_id': 4, 'end_character': 401, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '21486360', 'title': "Kievan Rus'", 'start_paragraph_id': 58, 'start_character': 0, 'end_paragraph_id': 58, 'end_character': 439, 'bleu_score': 0.970362113628587, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1619866242329402882}, 'section': 'Section::::History.:Final disintegration.\n'}]}]