>Ivan IV was the eldest son of Vasili III by his second wife Elena Glinskaya, and a grandson of Ivan III. He succeeded his father after his death, when he was three years old. A group of reformers united around the young Ivan, crowning him as tsar in 1547 at the age of 16. In the early years of his reign, Ivan ruled with the group of reformers known as the Chosen Council and established the Zemsky Sobor, a new assembly convened by the tsar. He also revised the legal code and introduced reforms, including elements of local self-government, as well as establishing the first Russian standing army, the streltsy. Ivan conquered the khanates of Kazan and Astrakhan, bringing the entire length of the Volga river under Russian control.