1044
This led directly to the Battle of Chester , where Æthelfrith of Northumbria seems to have killed the kings of Powys and ( possibly ) Gwynedd during an attack on the ecclesiastical community at Bangor-on-Dee .
 location: Chester; person: Æthelfrith of Northumbria; location: Bangor-on-Dee
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 location: Chester; person: Æthelfrith of Northumbria; location: Bangor-on-Dee