Complex sentence: The position of Mayor of Moscow was elected between 1991 and 2004, after which new legislation moved the election system to an indirect one in which parliamentary political parties and the President of Russia nominated a candidate who must then have been approved by the Moscow City Duma.
Split into simpler sentences: The position of Mayor of Moscow was elected between 1991 and 2004. The new legislation moved the election system to an indirect one in which parliamentary political parties and the President of Russia nominated a candidate who must then have been approved by the Moscow City Duma.