Complex sentence: Pedro de Luján (1500s-1536) was a Spanish nobleman, captain and conquistador of the Río de la Plata, who arrived in the expedition of his uncle, Pedro de Mendoza.
Split into simpler sentences: Pedro de Luján (1500s-1536) was a Spanish nobleman, captain and conquistador of the Río de la Plata. He arrived in the expedition of his uncle, Pedro de Mendoza.