In 1122, after heavy fighting with the Seljuks that involved at least 60,000 Georgians and up to 300,000 Turks, the troops of the King of Georgia David the Builder entered Tbilisi. After the battles for Tbilisi concluded, David moved his residence from Kutaisi (Western Georgia) to Tbilisi, making it the capital of a unified Georgian State. From 12-13th centuries, Tbilisi became a dominant regional power with a thriving economy (with well-developed trade and skilled labour) and a well-established social system/structure. By the end of the 12th century, the population of Tbilisi had reached 100,000. The city also became an important literary and a cultural center not only for Georgia but for the larger civilized world as well. During Queen Tamar's reign, Shota Rustaveli worked in Tbilisi while writing his legendary epic poem, The Knight in the Panther's Skin. This period is often referred to as "Georgia's Golden Age" or the Georgian Renaissance.