Sanahin and its nearby cousin Haghpat, shared in the fortunes and travails of the times, intertwined in history while each unique as a center of learning, religious study and font of spirituality.
The exact date for the founding of Sanahin is unknown. It is believed to have been founded in the 4th century when a St. N'shan (Holy Sign) cross was erected at the site. Sanahin is said to be the older monastery (its name in Armenian translates into "this one is older than that one").
Documentary evidence suggest that the structures date back to the reign of king Abbas Bagratuni (930s). The historians Kirakos Gandzaketsi and Vardan Areveltsi wrote that the first structure of the monastery, St. Astvatsatsin church, was built by Armenian immigrants from Byzantium who had rejected the Chalcedonian sect.
Sanahin later became the Kiurikian Seat of power, a royal patrimonial sepulcher (until mid-12th c.), and residence for the Kiurikian diocese (until mid-11th c.), resulting in the construction of many religious and civil structures. In both monasteries, especially in Sanahin, humanitarian sciences, music and medicine were studied, scientific treatises composed and artworks (mostly miniatures) painted.
Between them, Haghpat and Sanahin had more than 20 churches and chapels, annexes, sepulchers, bell-towers, an Academy (Magistros' seminary), book depositories, refectories, galleries, bridges and other monumental structures, to say nothing of numerous dwelling and service structures.
Like Haghpat, Sanahin was sacked during the Mongol invasion, which first captured the fortress Akner built halfway between them for protection. In 1996 Haghpat, and then Sanahin (1999) were jointly registered on UNESCO's World Heritage List.