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The use of mail as battlefield armour was common during the Iron Age and the Middle Ages , becoming less common over the course of the 16th and 17th centuries when plate armour and more advanced firearms were developed .
 Iron Age, Middle Ages
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:
 Iron Age, Middle Ages