In the sixteenth century, the Uzbeks established two strong rival khanates, Bukhoro and Khorazm. In this period, the Silk Road cities began to decline as ocean trade flourished. The khanates were isolated by wars with Iran and weakened by attacks from northern nomads. Between 1729 and 1741 all the Khanates were made into vassals by Nader Shah of Persia. In the early nineteenth century, three Uzbek khanates—Bukhoro, Khiva, and Quqon (Kokand)—had a brief period of recovery. However, in the mid-nineteenth century Russia, attracted to the region's commercial potential and especially to its cotton, began the full military conquest of Central Asia. By 1876 Russia had incorporated all three khanates (hence all of present-day Uzbekistan) into its empire, granting the khanates limited autonomy. In the second half of the nineteenth century, the Russian population of Uzbekistan grew and some industrialization occurred.