The Iussupovs were one of the wealthiest families in Russia at the end of the XIX Century.
Prince Nicholas Borissovich Iussupov (1827-1891) was at his death without heir. His daughter Zinaida Nicholaevna married Count Felix Felixovich Sumarokov-Elston (1856-1928). Count Sumarokov-Elston, following his marriage was declared by the Imperial Ukaz in 1885, heir of the title and the name of his father-in-law, heritage which he received at the death of the above in 1891 and therefore his full name and title became Prince Iussupov, count Sumarokov-Elston.
His son Felix (1887-1967) married in 1914 Grand Duchess Irina Alexandrovna, the niece of the Emperor Nicholas II, he was in December 1916, the instigator of the Rasputin murder.