A divided Islamic world offered feeble resistance to the Crusaders who consolidated their hold on the eastern Mediterranean and imposed their fiefdoms on the region. The Seljuks, preoccupied with defending their eastern flank against the Afghan Ghaznavids, had thinned out their western defenses. The pagan Turkish tribes across the Amu Darya on the northeastern frontiers were a constant menace....

The triumphant advance of Muslim armies across the inter-connecting landmass of Asia, Europe and Africa brought into the Islamic Empire large masses of people who were previously Christian, Zoroastrian, Buddhist or Hindu. Conversion to the new faith was slow. The conquering Muslims left the people of the territories alone as long as they paid the protective tax, jizya and did not interfere with...

En la industria de los materiales plásticos, la película de PVC y la película de vinilo son términos que a menudo se usan indistintamente, lo que puede generar cierta confusión. Sin embargo, aunque están relacionados, existen diferencias clave entre ambos materiales en cuanto a composición, características y aplicaciones. A...