In the East, at the beginning of the ninth century, the Jews were also reminded, in a disagreeable manner, that they had to expect scorn and oppression even from the best rulers. The reigns of the Abassid Caliphs, Haroun Alrashid and his sons, are regarded as the most flourishing period of the Caliphate of the East, but it is at this very time that Jewish complaints of oppression rise loudest. It is possible that in re-enacting Omar's law against the Christians (807), Haroun also made it applicable to the Jews; for they were compelled to wear a distinctive badge of yellow on their dress, in the same way as the Christians were obliged to wear blue, and they had to use a rope instead of a girdle. When, after his death (809), his two sons, Mahomet Alemin and Abdallah Almamun, for whom their father had divided the Caliphate into two parts, engaged in a destructive civil war, throughout the whole extent of the great empire, the Jews, especially those in Palestine, experienced severe persecution. The Christians, however, were their companions in misfortune. During the four years (809-813) of this fratricidal struggle, robbery and massacre seem to have been the order of the day. The sufferings were so terrible, it seems, that a preacher of those times declared them to be a sign of the speedy coming of the Messiah. "Israel can only be redeemed by means of penitence, and true penitence can only be evoked by suffering, affliction, wandering, and want," declared this orator by way of consolation of his afflicted congregation. In the civil war raging between the two Caliphs, he fancied he saw the approaching destruction of the Ishmaelite rule and the approach of the Messianic empire. "Two brothers will finally rule over the Ishmaelites (Mahometans); there will then arise a descendant of David, and in the days of this king the Lord of Heaven will found a kingdom which shall never perish." "God will exterminate the sons of Esau (Byzantium), Israel's enemies, and also the sons of Ishmael, its adversaries." But these, like many others, were delusive hopes. The civil war, indeed, shook the Caliphate to its foundations, but did not destroy it. Alemin was killed, and Almamun became the sole ruler of this extensive empire.