By the end of the 11th century, Georgia finally possessed sufficient forces to repel the Seljuk hordes, but they still lacked a strong and charismatic enough leader to rally the people and to organize the struggle against the enemy. The Georgian leadership would need to take decisive measures to resuscitate the flagging country. Due to his inability to deal effectively with the ceaseless onslaught of the Seljuk forces, Giorgi II abdicated the throne in favor of his 16-year-old son David, later known as David the Builder (1089-1125). David became possibly the greatest monarch in the Georgian history. Personally leading his loyal forces, he attacked the Seljuks and, in routing them, allowed the peasants who had fled to the mountains to return to their land. He gradually expelled the Turks from Kartli. Fortunately, the simultaneous appearance of Crusader Knights in Asia Minor and Syria divided the Turks’ attention, weakened them, and forced them to divert a significant portion of their military resources towards the new threat in the south. After winning several victories in 1099, David stopped paying tribute to the Seljuk Sultan; however, the final liberation of all Georgian lands required a more efficient and professional army and further centralized power.By the early 12th century, the size of David’s army swelled to 40,000 men. In 1104 he finally drove the Turks completely from Kartli and Kakheti. In 1105, he defeated a large Turkish army in the Battle of Ertsukhi. From 1110-1118, he liberated the towns of Samshvilde, Rustavi, Gishi, Kubala, and Lore. Unfortunately, the capital city of Tbilisi was still occupied by the invaders and part of the Georgian army had sworn fealty to large landed nobility, who were not always loyal to the King. At the same time, incessant wars kept the most productive part of the population away from home and farming. To solve this problem David IV augmented his army with 40,000 Kipchak mercenaries from the north Caucasian steppes, whom he invited to settle in Georgia with their families. The Sejuk Sultan Mahmud began to worry that he might lose the Caucasus and ordered one of his best Generals, Radjin Al-Din Ilguzi (who had earned his reputation fighting against the Crusaders), to lead the Coalition Army of Turkish soldiers against Georgia. On August 12, 1121, near Didgori, David the Builder’s Army clashed with the numerically superior forces of Radjin Al-Din Ilguzi in an enormous battle. King David IV’s decisive victory allowed him to retake Tbilisi in 1122 and force the Turks out of their last stronghold, Dmanisi, in 1123. Following the liberation of Tbilisi, David the Builder relocated the capital there from Kutaisi. In 1124, at the request of the citizens of the Armenian city of Ani, the Georgian army liberated Ani, expanding the southern borders of the Georgian Kingdom up to the Araxes river basin. King David IV died on January 24, 1125. The modern flag of Georgia began as the military standard of King David the Builder.
The Georgian Kingdom reached its zenith in the early 13th century. The years from the early 12th to early 13th century have been widely called “Georgia's Golden Age” or “the Georgian Renaissance” from the reign of David the Builder to Queen Tamar. This early Georgian renaissance, which preceded its European analogue, was characterized by the flourishing of romantic-chivalric traditions, breakthroughs in philosophy, and an array of political, social, and organizational innovations, including an expansion of religious and ethnic tolerance. The Golden age of Georgia left a legacy of great cathedrals, romantic poetry, and literature such as the epic poem “The Knight in the Panther’s Skin.”
King David the Builder placed a great value on the education of his people. During the reign of David the Builder many schools and academies existed or were built throughout Georgia, first among which is Gelati Academy. A renowned historian of King David refers to Gelati Academy as "a second Jerusalem of all the East for learning of all that is of value, for the teaching of knowledge - a second Athens, far exceeding the first in divine law, a canon for all ecclesiastical splendor." Life of David: King of Kings, translated by Katharine Vivian, manuscript, p.12.
Gelati Academy was established during a period of developed feudalism—it answered the needs of the day, prefiguring the ideological movement that paved the way for the Georgian Renaissance. In addition to Gelati, there were also other scholarly centers in Georgia at that time. There was a school of higher-education Iqalto - the Iqalto Academy. Its existence is attested to by the ruins preserved in the yard of the monastery, most probably forming a single building. Windows and the base of a pulpit are discernible. The founder and first rector of the academy was Arsen Iqaltoeli who came to Iqalto from Gelati in the 1120s. Historical sources also mention an academy at Gremi during this time period.Intensive literary, philosophical, and translation work was carried on at Georgian centers of culture and education outside Georgia as well, including the Iviron monastery on Mt. Athos, the monastery on the Black Mountain in Syria, and Petritsoni monastery in Bulgaria. In this period, a number of original works were written and important literary works of universal cultural value were translated into Georgian, facilitating the advancement of national scholarship and literature.