The monastery experienced its heyday in 979. At that time the Kingdom of Tashir-Dzoraget was established and Sanahin was raised as a bishopric. Sanahin is mentioned in medieval manuscripts from the early 10th century.

According to reports by chronicler Stephan from Taron, in the 11th century there were 500 monks living and working in the monasteries of Sanahin and Haghpat. Towards the end of the 10th century, Sanahin had already become the most important spiritual center of the whole Kingdom of Tashir-Dzoraget, and additionally, one of the most famous monasteries of Armenia. In the academy of the monastery, which is associated with the name of Grigor Magistros Pahlavuni, people were taught septem artes liberals, the “seven liberal arts’’, as well as medicine, painting and in particular, the art of miniature painting. Monks of Sanahin were highly respected and they often accompanied ambassadors abroad as consultants.