63590
However , by the 21st century , the meaning of " modern history " had shifted to refer either to the history of the modern period following the middle ages , or of the late modern period following the early modern period .
 modern period, early modern period
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 modern period, early modern period