Hovhannes Sarkavag (XI-XII centuries) is one of the most unique, extraordinary phenomena in the history of Armenian culture, who left a rich, multi-genre heritage of theological literature. His modest name should take its worthy place not only among the pearls of Armenian science and culture, but also among medieval all Christian intercultural values.

The multi-diverse works by Hovhannes Sarkavag: spiritual-theological literature, historiography, philosophy, pedagogy, mathematics textbook, cosmological-calendar are aimed at enhancing the role and significance of the Armenian Apostolic Church (as a homeland, culture, education, science and faith), becoming the most important pledge in overcoming the various religious and political challenges of the time.

This book examines in detail the biography of Hovhannes Sarkavag. Also his literature achievements are briefly described in the presented work. It examines Sarkavag’s calendar heritage in more detail.

The legacy of both theoretical and practical issues of the volume of Hovhannes Sarkavag, which has reached us in a fragmentary state, with numerous copies and editions, forms a collection. The new interpretation of the Armenian 532-year Easter moving Calendar and the creation of the project of the Armenian stationary calendar are connected with the name of Hovhannes Sarkavag. He was entrusted with the regulation of calendrical issues of the second cycle of 532-year calendars, related to the features of Armenian movable and immovable calendars.

In this book we have restored the title of the calendar collection: “Meknutyun Tumaris Haykaznya”(“Interpretation of the Armenian Calendar”), which was created in 1094. Hovhannes Sarkavag created two 532-year calendars for the 2nd cycle, one of them according to the Roman calendar style, the second according to the Armenian fixed calendar style. And on the basis of the list of dates created by this Armenian fixed calendar, the system of the Armenian Small Calendar was formed, the first year of which corresponds to the current year 1085, as well as the 534th year of the Armenian Great Calendar.

The difference between the Armenian Great and Roman Calendars until 1004 was 551/552 years, and when Navasard 1 crossed the vernal equinox on March 20, one year was added to the Armenian Great year due to the end of the 1460-year Haykian cycle, and this year was added to the years of the first cycle of the Armenian 532-year Calendar, as a result of which the Armenian cycle did not end in 532, and in 533, and the Sarkavag Calendar began in 534 of the Armenian Great Calendar.

Although the theoretical beginning of Sarkavag Calendar is Navasard 1 = August 11, in practice its beginning as a calendar unit is the beginning of the Armenian Church Year — the Day of Christmas and Epiphany — January 6 = 29 Kagots (Town), the fasting days of which are determined by the beginning of the Roman Calendar — January 1. However, Sarkavag, as a rational thinker, usually accepts the beginning of time as the beginning of spring, that is, the beginning of the natural economic year, which corresponded to the Hebrew 1 Nisan = 22 March = 14 Areg (1 Areg = 9 March).

The Calendar Year of Hovhannes Sarkavag for 2 years older than the current year. When calculating according to his rule, it is necessary to subtract two years from the current year to bring it in line with the Dionysian years.

In the second part of the fourth chapter of the book presents the 532-year Easter lists of Hovhannes Sarkavag according to the Julian and Armenian Sarkavag calendars. We completely restored the last one. In the second part of the fourth chapter presents partially corrected calendars of 15 nations, called "Azgats Aznvakanons" ("Aznvacanons of the Nations"), which are compared to each other.