What historical event is mentioned in the text regarding Ivan III and the Golden Horde?

The text mentions the 'Стояние на Угре' (Standing on the Ugra River) which is described as a significant event that marked the liberation of Rus' from the 'ordynskogo vladichestva' (Tatar-Mongol yoke). It quotes N. Karamzin saying, 'Here is the end of our slavery'.