Why was the timing of Pizarro’s third conquest into South America perfect?

Pizarro's men massacre the Incans and capture Atahualpa, forcing him to convert to Christianity before eventually killing him. Pizarro's timing for conquest was perfect. ... Though he had nearly 80,000 soldiers with him in the mountains, Atahualpa consented to attend the feast with only 5,000 unarmed men.