Question: Cynfarch Oer, was probably a 6th-century king of the Sub-Roman realm of Rheged, was one of the kingdoms of the "Hen Ogledd" ("Old North"), the Brittonic-speaking region of what is now Northern England, and southern Scotland, during the post-Roman era, and which time period?
{'answer': 'Early Middle Ages', 'supporting_facts': [['Cynfarch Oer', 0], ['Rheged', 0]]}