Complex sentence: He was originally born as a girl child named'Shikhandini' to Drupada, the king of Panchala, and he had been born in an earlier lifetime as a woman named Amba, who was rejected by Bhishma for marriage due to his oath of lifelong celibacy.
Split into simpler sentences: He was originally born as a girl named'Shikhandini' to Drupada, the king of Panchala. In a previous lifetime, Shikandini was a woman named Amba, who was rejected by Bhishma for marriage due to his oath of lifelong celibacy.