The exact date of the birth of Ali is not known with any degree of certainty. According to traditions, Ali was born on the thirteenth of "Rajab" in the 28th year of the Elephant Era. The Elephant Era according to the annals of Arabia commenced when Abraha the Christian Viceroy of Yemen invaded Makkah with the intention of destroying the Kaaba, and shifting the center of pilgrimage to Yemen. The invasion failed and the Christian army had to beat a retreat without achieving its object. That marked the retreat of Christianity from the heartland of Arabia and paved the way for the rise of Islam. The Holy Prophet of Islam was born in the Year of the Elephant. According to scholars the Year of the Elephant corresponds to the year 571 of the Christian era. On this basis, the year of the birth of Ali would have to be placed around 599 or 600 C.E. Anyhow Ali was at the junction of the two centuries, the sixth and the seventh.