Simplify the following text for a Grade 10 native English-speaking person.
Original: Modern scholars have come to question the existence of at least the first nine emperors ; and KÅ gen 's descendant , Emperor Sujin is the first many agree might have actually existed .
Simplified: Some scholars question the existence of the first nine emperors . These critics consider KÅ gen 's grandson ( Emperor Sujin ) to be the earliest to have actually existed .