80139
Ivan IV had introduced a new strategy , relying on tens of thousands of native troops , cossacks and tartars , instead of a few thousand skilled troops and mercenaries , as practiced by his adversaries .
 Ivan IV
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Ivan IV