Which emperor ruled during the byzantine empire and attempted to restore the western roman territories to a time prior to its fall in the 400s?

The emperor who ruled during the byzantine empire and worked hard to try to restore the western roman territories to its glory prior to the fall in the 400s was Emperor Justinian. Name Justinian I, he was more often referred to as Saint Justinian the Great or Justinian the Great, this emperor served from 572BC until 565BC