The Nestorians, a Christian religious sect in Gondisāpūr, India, planted sugar cane in Persia about 500 A.D. When Heraclius,[8] the Byzantine emperor, pillaged the palace of Dastargerd, Persia, in 627 A. D., solid sugar was taken among the other loot.[9] This is the first authentic evidence of crystallization. At the time of the Arabian conquest in the year 639, sugar was “prepared with art” in Gondisāpūr; and its manufacture on a large scale was carried on at Shuster, Sūs[10] and Askar-Makram[11] through the Middle Ages. Thaálibí, a writer of the eleventh century, says that Askar-Makram had no equal for the quality and quantity of its sugar, “notwithstanding the great production in Irāk, Jarjān and India.” It used to pay fifty thousand pounds of sugar to the Sultan in annual tribute.[12] Persian physicians of the time attributed extraordinary healing powers to sugar, and used it freely in the practice of their art. Mohammed’s[13] religious wars carried the knowledge of sugar throughout the cities of the then civilized world. The Arabs first learned of it when they overran Persia. They took to it eagerly, and under their rule a great number of plantations were started. Artificial irrigation was employed in the growing of the cane, and the juice was expressed by means of millstones. At this period, however, sugar was looked upon as a rare and costly luxury, to be indulged in only by the wealthy, and sparingly even by them. Arabian doctors who were well advanced in learning gave sugar an important place in their pharmacopœia. The Moslem armies took it westward with them; and when Amru[14] conquered Egypt (640-646 A. D.), it was introduced in that country. Careful methods of cultivation, coupled with the Egyptians’ intimate knowledge of chemistry, brought about excellent results. This cultured people had a simple process for purifying and recrystallizing saltpeter, and they soon found that sugar could be similarly treated. The first crystals were remelted; and to the liquor so obtained albumen and lime were added. The precipitated impurities were removed by filtration, and the clear syrup boiled down to a grain once more. The syrup, or mother-liquor in which these grains remained after boiling, was eliminated by washing, leaving the white sugar crystals, which in point of quality far surpassed any product then known. From this time forward, the traffic in sugar began to gain in importance and volume. Nasiri Khosrau, in his account of his travels in Egypt in the eleventh century, narrates that at the celebration of the great Ramazán feast, the Sultan’s table was decorated with sweetmeats consisting entirely of marzipan[15] modeled into shapes of orange trees and statues.