Complex sentence: After a summer break, Nashwan's next target was to be the Prix de l'Arc de Triomphe at Longchamp, and to prepare for this he was sent to the Prix Niel.
Split into simpler sentences: After a summer break, his next target was to be the Prix de l'Arc de Triomphe at Longchamp. To prepare for this race, he was sent to the Prix Niel.