Era of Emperor Diocletian 29 August 284 A.D.
 
 

In Anno Domini (Ab incarnatione Domini)
    Dionysius Exiguus, a computista,  525 A.D. compiled a table for calculating Easter and began his chronology with the birth of Jesus

Byzantine Era --- Anni ab origine mundi (5508 B.C.)
Hegira of Mohammed (622 A.D.)
Spanish Era  38 B.C.
 
 

Modern Eras