Pursuant to the death of Batu Khan, he was replaced by his little brother, Berke Khan (1257). Berke Khan minted coins in his name and disconnected its relations with Karakorum and declared his independency. Furthermore, he founded the city of Yenisaray and declared this city as the capital city. Meanwhile, the other sons of Jenghiz Khan had been involved in conflicts among each other and they had started to fight for the throne of the Great Khanate with each other. Berke Khan evaluated the situations properly. Before the war for the Great Khanate, he firstly took side with Artik Böke. However, Kubilay Khan won this war and therefore, his relations with the Great Khanate were totally disconnected.
We have stated that the region of Harezm was under the possession of Chagatai Khan as a result of the sharing of Jenghiz Empire. This country was called as Chagatai's Country or Chagatai's Lands. At that time, Algu Khan dominated in these regions. When Berke Khan was prepared to organise a military expedition towards the Caucasus, Algu Khan had expanded his borders that would transcend the borders of the Golden Horde. Therefore, they were on strained terms. On the other hand, when Ilhanli ruler Hulagu penetrated into the Caucasus, he had to fight with them. Both of these two rulers that were brothers wanted to establish dominion in the affluent Azerbaijani lands. Therefore, a war broke out between them. Berke Khan totally defeated Hulagu in a crushing manner.
The fight of Berke Khan with the Ilhanli State caused the establishment of a close relationship among the Mamelukes that had come from the Kipchak countries and established a state in Egypt.
Berke Khan who established friendly relations with the Mameluke sultan, Baybars started to get interested with the Byzantine. He sent an army composed of 20 thousands of people under the command of his nephew, Nogay towards the south of Danube River. He defeated the Byzantine army and annihilated it. Through this military expedition, he saved Keykavus II that was taken prisoner in Istanbul and took him to the Crimea.