Question

What was Jusinian I's role in the decline of the Byzantine Empire

Answer 1

He was terrible with money and overextended the military. By the time he died, the military had to actually shrink itself down because he lacked the money to pay for all of the soldiers. It was one of the reasons why many of the lands that Justinian reclaimed that used to be part of the Roman Empire fell back into 'barbarian' hands in the century after his death.