For a period of time, their mother, Grand Duchess Anna Vasilyevna, sister of Prince Ivan III of Moscow, ruled the duchy as regent.
[2] The internal politics of Ivan IV of Ryazan was focused on keeping Ryazanian boyars from entering Moscow court.
[1] On June 9, 1483,[1] he concluded a treaty with his maternal uncle, Grand Prince Ivan III of Moscow, which, as a matter of fact, put the Duchy of Ryazan in the position of a vassal principality.
[2] Dmitry Ilovayski argued that the position of the Grand Prince of Ryazan under this treaty was similar to a viceroy, rather than a ruler.
[2] Ivan IV of Ryazan had to admit the towns of Teshilov, Venyov and Rostovets as domains of Moscow, and never attempt to invade Yelets.
[3] In 1493 Ryazanian troops headed by Prince Fyodor Vasilyevich and his warlord Ivan Inka Izmaylov had to capture Serpeysk and Mezetsk for Moscow, taken by Lithuanians prior to it.