What event marked the beginning of the disintegration of the Golden Horde into a separate khanate?

The fourteenth century was marked by significant changes in the political structure of the Golden Horde state. Signs of decentralization began to emerge with increasing force. Nevertheless, until the end of the fourteenth century, the unity of the horde was preserved by the event that became the catalyst for the disintegration of the Golden Horde, a severe military defeat inflicted on it by the troops under the leadership of Tamerlane and accompanied by the plundering and decline of the traditional centers of the state’s economy. Already starting from the twenties of the fifteenth century, new state formations appeared on the world map, which were formerly parts of a single Golden Horde.