Complex sentence: The Rallye Sanremo is a rally competition that was part of the FIA World Rally Championship from 1973 to 2003, when it was replaced by Rally d'Italia Sardegna on the island of Sardinia, in hosting the Italian round of the WRC.
Split into simpler sentences: The Rallye Sanremo is a rally competition that was part of the FIA World Rally Championship from 1973 to 2003. It was replaced by Rally d'Italia Sardegna on the island of Sardinia, in hosting the Italian round of the WRC.