This is accepted as the way the Crimean Khanate became independent, which kicked off a rivalry between Crimea and the Great Horde.[1]: 15–16 Küchük Muhammad drove out Ulugh Muhammad from the heartland of the Golden Horde in 1438, being proclaimed Khan in Sarai.[7]: 300 Throughout the rules of Küchük Muhammad and Sayid Ahmad I, the Tatars tried to force their Russian subjects to pay taxes, invading them in 1449, 1450, 1451 and 1452. These attacks led to retaliation from the Polish-Lithuanian Commonwealth, who allied with the Crimean Khanate. At the same time, envoys from Lithuanian nobles who were unhappy being under a Polish-dominant Commonwealth brought gifts to Sayid Ahmad, who invaded Poland-Lithuania in 1453.