Russian Empire
Though the Empire was only officially proclaimed by Tsar Peter I following the Treaty of Nystad (1721), some historians would argue that it was truly born either when Ivan III of Russia conquered Veliky Novgorod in 1478, or when Ivan the Terrible conquered the Khanate of Kazan in 1552. According to another point of view, the term "Tsardom", which was used after the coronation of Ivan IV in 1547, was already a contemporary Russian word for empire.
Rurik dynasty
The Yuryeviches were founded by Yuriy Dolgorukiy, the founder of Moscow and spread vastly in the north-east. Yuri's son Vsevolod the Big Nest was Prince of Vladimir-Suzdal, a precursor state to the Grand Principality of Moscow and thus of the Russian Empire. Vsevolod's son Konstantin of Rostov was Prince of Rostov and the progenitor of various "Rostov" princely lines. Another son, Ivan Vsevolodich, was Prince of Starodub and progenitor of a number of extant lines, most notably the Gagarin line.