The Library of Alexandria is considered to be the largest and greatest library of the ancient world. Established by the Ptolemaic dynasty, one of the heirs to Alexander the Great's empire, it was the premier centre of learning in the Mediterranean. It survived in full glory for three hundred years until a fire broke out during the Roman occupation of Egypt. Damaged, the Library still survived centuries later, but its glory days were over. A long slow decline began, until paganism was outlawed in the Roman Empire in AD 391, and the Library was destroyed. All reference to the Library of Alexandria ends with the rise of the Rashidun Calipate, nearly a millennium after its establishment.