Durdzuk was the name used historically by Georgians for the Chechens. The Durdzuks constructed numerous kingdoms, notably Durdzuketi; and they were noted for their exceptionally fierce devotion to freedom and their ability to resist invaders, ranging from the Arabs to the Scythians to Turkic peoples to the Mongolian invaders. They seemed also to have been employed as mercenaries by various parties. They had a written language using Georgian script (It is not known whether they spoke that language however.), but most of these writings have been lost, with only a few pieces surviving. After the 14th-century Second Mongol Invasion of Durdzuketi and the destruction wrought by the two invasions (including, as Amjad Jaimoukha notes, the destruction of their memory of their past), they radically changed their culture. They became known as the Ichkeri (Turkic for "freedom people"), and their land as Ichkeria. It was then (as the Ichkeri) that the teip system became formalized into its well-known modern form. The term Ichkeri was also used to refer to the Ingush (for the most part), until the Ingush broke off. The name Ichkeri is a cognate of the names used for "Chechen" and "Chechnya" in many languages at that time, including Michiki (Lak) and Mitzjeghi. Only after the Russian conquest in the 19th century did the name "Chechen" become the internationally accepted name for the people of Chechnya.