In 1241 The Kipchak Khanate, or Golden Hordes began invasions.
Led by Batu Khan and Subuta, his ruthless general, these Mongol hordes swept across the Duchy with blazing speed.
Prior to this some men had answered the calls of the Order of the Bretheren of the Sword (later to be known as Teutonic Knights). In an attempt to stop Zolotaya Orda before the sack of Kiev in 1239.
Because of the forewarning, Mieczyslaw, did not resist Batu Khan and so, like Smolensk was spared the terrible scourge of the Mongol vengance, such as at Kozelsk. Batu Khan seemed content to ignore Mieczyslaw, so long as tribute was paid, so the otherwise defenceless city paid the tribute.
Further invasions swept across Ducal lands in 1259 and 1287, however effective rule was only thru Zolotaya Orda favor until 1481, when after the Great stand on the Ugra river, Zolotaya Orda was defeated and forever gone from The Duchy of Mieczyslaw.
With the victory over the Golden Horde Ivan III declared himself Tsar of all the Russias, of which at least parts of The Duchy of Mieczyslaw were included.