Complex sentence: The Spanish marched on Cuernavaca even before taking the Aztec capital of Tenochtitlan, led by Gonzalo de Sandoval and joined later by the conquistador, Hernán Cortés.
Split into simpler sentences: The Spanish marched on Cuernavaca even before taking the Aztec capital of Tenochtitlan. They were led by Gonzalo de Sandoval and he was joined later by the conquistador, Hernán Cortés.