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The northern part of Northumbria , and perhaps the whole kingdom , had probably been ruled by Ealdred son of Eadulf since 913 .
 Northumbria, Ealdred, Eadulf
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Northumbria, Ealdred, Eadulf