Complex sentence: In 1613, following the fall of the House of Rurik and years of interregnum (Time of Troubles), the zemsky Sobor offered the crown to Mikhail Romanov, who acceded to the throne as Michael I, the first Tsar from the House of Romanov.
Split into simpler sentences: In 1613, following years of interregnum (Time of Troubles), the zemsky sobor offered the Russian crown to Mikhail Romanov. He acceded to the throne as Michael I, becoming the first Tsar of Russia from the House of Romanov.