Simplify the following text for a Grade 16 native English-speaking person.
Original: In consequence the Kingdom of East Francia would have lasted from 843 to the coronation of Duke Henry I of Saxony in 919 ; though more commonly , the Holy Roman Empire is thought to begin with the Coronation of Emperor Otto I in Rome on February 2 , 962 as a translatio imperii from the Frankish Empire .
Simplified: If the beginning of the Holy Roman Empire is thought to have happened at the same time as the rise of the Ottonian dynasty , the kingdom of East Francia lasted from 843 to when Duke Henry I of Saxony became a monarch on in 919 ; or it could have began in 962 , when Otto the Great became a monarch ( translatio imperii ) .