Complex sentence: Cardinal Richelieu died in 1632, and Louis XIII died in 1643, and Poussin's Paris sponsor, Sublet de Noyer, lost his position, but Richelieu's successor, Cardinal Mazarin, began to collect Poussin's works.
Split into simpler sentences: Cardinal Richelieu died in 1632, and Louis XIII died in 1643, and Poussin's Paris sponsor, Sublet de Noyer, lost his position. However, Richelieu's successor, Cardinal Mazarin, his successor, Cardinal Mazarin, began to collect Poussin's works.