The division of Armenia after the Peace of Acilisene.
The Peace of Acilisene was a treaty between the East Roman Empire and the Sassanid Empire sometime between 384 and 390 (usually dated to 387) which divided Greater Armenia between these two empires. Persia received the greater share. By this treaty the Byzantine Empire/East Roman Empire also finally admitted the loss of Kartli-Iberia to Sassanid Iran. From this point on, Iranian influence grew once again in eastern Georgia, and Zoroastrianism appeared to have become something like the second established religion alongside Christianity.