The author of many works, Aristakes's most valuable contribution in the field of the historiography was his History About the Sufferings Occasioned by Foreign Peoples Living Around Us,[b] which describes Bagratid Armenia's relations with the Byzantine Empire and Georgia and the devastating Seljuk invasions of the 11th century and the torture of Christians by the Seljuks.The date of his birth has been estimated as 1002, and he is assumed to have died in old age not long after completing his history in 1079.As a vardapet, he was well versed in Christian theology and rhetoric and knew Greek and probably several other languages.Composed of 25 chapters and a unique colophon, Aristakes describes the Seljuk invasions in 1047-48 through the capture of Ani in 1064 and the Battle of Manzikert in 1071.[4] There are more than 25 extant manuscripts of Lastivertsi's history, the oldest of which was begun in the 14th century and completed in 1567.