Many states had been "de facto" independent kingdoms long before 907 as the Tang dynasty's ability to control its officials gradually waned, but by this point, they had now been recognized as such by foreign powers. After the Tang had collapsed, warlords who controlled the Central Plain crowned themselves as emperors. During the 70-year-long period, there was near constant warfare between the emerging kingdoms and alliances they formed. All had the ultimate goal of controlling the Central Plain, which would have granted legitimacy over currently held territories and the rest of China as Tang’s successor.