Zahirul Hasan's book " Eight Hundred Years of Muslims in Bengal " gives a very logical explanation on this subject. There are also contradictions between what Mr. Eaton and many other authors have found, and there are contradictions. A diagram emerges I am trying to highlight those issues Before that I highlighted the chronology of this subject I also highlighted some chronicles outside Bengal , the effects of which were far-reaching in Bengal Three centuries --- Buddhist predominance in Bengal 4 --- 5 centuries Gupta era 7th century --- Shashankar's reign 612 --- Arab conquest of the Arab general Mohammad bin Qasim 942 century --- According to folklore , the arrival of five Brahmins from Kanyakubja to Bengal 1095 _ 1099 --- Battle of the First Crusade 10 --- 12th century --- The earliest examples of Bengali literature Charyapad 1204 --- Bakhtiyar Khilji's Nadia conquest 1207 --- Genghis Khan's war campaign in Central Asia 1211 --- The beginning of the Sultanate rule in India 1200_1300- In the meantime, at some point or the other, the copper-plated port ceased to function due to lack of navigability of the river . At this time King Louis was defeated and captured by Al Moazzem Turan Shah of the Egyptian Ayyubid dynasty 1257 --- The fall of Baghdad in the Mongol invasion 1300 (approximately) --- Establishment of the Ottoman Empire 1301 - 1322 --- Reign of Shamsuddin Firoz Shah 1341 --- Masnad of Bengal Ali Shah