Lasting more than two centuries, the Golden Age came to a gradual end due to persistent invasions of nomads, such as Mongols, as well as the spread of Black Death by these same nomadic groups. Georgia further weakened after the Fall of Constantinople, which effectively marked the end of the Eastern Roman Empire, Georgia's traditional ally. As a result of these processes, by 15th century Georgia fractured and turned into an isolated enclave, largely cutoff from Christian Europe and surrounded by hostile Turco-Iranic neighbors. Georgia's decline resulted in "emasculation" of its image in Russian Imperial perceptions, which systematically overlooked the nation's origins and instead portrayed it as a vulnerable, feminine "orient" in need of imperial protection. Conversely, for Georgia the Golden Age forms an important part of its status as a once-powerful and ancient nation that maintained relations with Greece and Rome.
The Golden Age began with the reign of David IV ("the builder" or "the great"), the son of George II and Queen Helena, who assumed the throne at the age of 16 in a period of Great Turkish Invasions. As he came of age under the guidance of his court minister, George of Chqondidi, David IV suppressed dissent of feudal lords and centralized the power in his hands to effectively deal with foreign threats. In 1121, he decisively defeated much larger Turkish armies during the Battle of Didgori, with fleeing Seljuq Turks being run down by pursuing Georgian cavalry for several days. A huge amount of booty and prisoners were captured by David's army, which had also secured Tbilisi and inaugurated a new era of revival.
To highlight his country's higher status, he became the first Georgian king to reject the highly respected titles bestowed by the Eastern Roman Empire, Georgia’s longtime ally, indicating that Georgia would deal with its powerful friend only on a parity basis. Due to close family ties between Georgian and Byzantine royalty - Princess Martha of Georgia, aunt of David IV, was once a Byzantine Empress Consort - by 11th century as many as 16 Georgian ruling princes and kings had held Byzantine titles, David becoming the last one to do so.
David IV made particular emphasis on removing the vestiges of unwanted eastern influences, which the Georgians considered forced, in favor of the traditional Christian and Byzantine overtones. As part of this effort he founded the Gelati Monastery, a UNESCO World Heritage Site, which became an important center of scholarship in the Eastern Orthodox Christian world of that time.
David also played a personal role in reviving Georgian religious hymnography, composing the Hymns of Repentance (Georgian: გალობანი სინანულისანი, galobani sinanulisani), a sequence of eight free-verse psalms. In this emotional repentance of his sins, David sees himself as reincarnating the Biblical David, with a similar relationship to God and to his people. His hymns also share the idealistic zeal of the contemporaneous European crusaders to whom David was a natural ally in his struggle against the Seljuks.
The kingdom continued to flourish under Demetrius I, the son of David. Although his reign saw a disruptive family conflict related to royal succession, Georgia remained a centralized power with a strong military, with several decisive victories against the Muslims in Ganja, gates of which were captured by Demetrius and moved as a trophy to Gelati.
A talented poet, Demetrius also continued his father's contributions to Georgia's religious polyphony. The most famous of his hymns is Thou Art a Vineyard, which is dedicated to Virgin Mary, the patron saint of Georgia, and is still sung in Georgia's churches 900 years after its creation.