The Kingdom of Dacia , under King Decebalus , had become a threat to the Roman Empire , and defeated several of Rome 's armies during Domitian 's reign ( 81 - 96 ) .
The First Roman -- Dacian War took place from 101 to 102 AD .
The Dacian War     , under King Decebalus , had become a threat to the Roman Empire , and defeated several of Rome 's armies during Domitian 's reign ( 81 - 96 ) .
The First Roman -- Dacian War took place from 101 to 102 AD .