David Marshall Lang 
Lives and Legends of the Georgian Saints [PDF ebook] 

With the exception of the life of St. Nino, none of the biographies here had been previously translated into English when this book was originally published in 1956. The lives of the Georgian saints are rich and many-sided, not dry chronicles of monkish trivialities. They contain vivid descriptions of life in the Caucasus, Byzantium and Palestine. They give the reader insight into the history and aspirations of an important branch of the Eastern Church and into its relationships with Zoroastrian Persia, the Arab Caliphate, the Imperial Court of Constantinople and the whole world of mediaeval Christendom.