Battle for faith.
The conversion to Christianity was inevitably to bring in its wake complications of a political nature and to arouse grave anxieties in neighboring Persia. The Sassanian Persians took advantage of Armenia's inner weakness and launched a campaign to stamp out Christianity there and replace it with Mazdaism. Under this common threat, the princes, nobility and the people of Armenia rallied, and in 451 under the leadership of the Commander-in-Chief (sparapet) Vardan Mamikonian the Armenians heroically faced the Persians at Avarayr in defense of their faith and national heritage. Heavily outnumbered, they were defeated; Vardan Mamikonian and many valiant men fell fighting. But guerrilla warfare continued in the mountainous regions. Vahan Mamikonian, a nephew of Vardan, continued the struggle. This time the Persians, realizing the futility of their policy, were obliged to come to terms with the Armenians. Freedom of religious worship was restored with the Treaty of Nvarsag.

The Bagratid dynasty.
In the 7th century, the mighty Arabs stormed into Armenia and conquered the country. Beginning in the 9th century, Armenia enjoyed a brilliant period of independence when the powerful Bagratid Dynasty asserted political authority. Resumption of international trade brought prosperity and the revival of artistic and literary pursuits. The capital of Ani grew to a population of about 100,000, more than any urban center in Europe. Religious life flourished and Ani became known as the "city of one thousand and one churches." In the middle of the 11th century, most of Armenia had been annexed by Byzantium.

The Cilician kingdom of Armenia.
The destruction of the Bagratid Kingdom was completed by raids of new invaders, the Seljuk Turks from Central Asia. With little resistance from weakened Byzantium, the Seljuk Turks spread into Asia Minor as well as the Armenian highlands. This invasion compelled a large number of Armenians to move south, toward the Taurus Mountains close to the Mediterranean Sea, where in 1080 they founded, under the leadership of Ruben (Rubenid dynasty), the Kingdom of Cilicia or Lesser Armenia. Close contacts with the Crusaders and with Europe led to absorbing Western European ideas, including its feudal class structure. Cilician Armenia became a country of barons, knights and serfs. The court at Sis adopted European clothes. Latin and French were used alongside Armenian. The Cilician period is regarded as the Golden Age of Armenian Illumination, noted for the lavishness of its decoration and the frequent influence of contemporary western manuscript painting. Their location on the Mediterranean coast soon involved Cilician Armenians in international trade between the interior of Western Asia and Europe. For nearly 300 years, the Cilician Kingdom of Armenia prospered, but in 1375 it fell to the Mamelukes of Egypt. The last monarch, King Levon VI, died at Calais, France in 1393, and his remains were laid to rest at St. Denis (near Paris) among the kings of France.