ships. The Chinese Muslim envoy Ma Huan wrote about a flourishing shipbuilding industry and Bengal's significant seaborne trade. The muslin trade in Bengal, the production of silk and the development of several other crafts were indicated in Ma Huan's list of items exported from Bengal to China. Bengali shipping co-existed with Chinese shipping until the latter withdrew from the Indian Ocean in the mid-15th-century. Bengali port cities like Chittagong and Satgaon were possibly entrepots for importing and re-exporting goods to China. Mughal period The Mughal Empire eventually controlled the region under its Bengal Subah viceregal province. The Mughal Emperors considered Bengal their most prized province. Emperor Akbar redeveloped the Bengali calendar. In the 16th-century, many Ulama of the Bengali Muslim intelligentsia migrated to other parts of the subcontinent as teachers and instructors of Islamic knowledge such as Ali Sher Bengali to Ahmedabad, Usman Bengali to Sambhal and Yusuf Bengali to Burhanpur. The process of Islamization of eastern Bengal, now Bangladesh, is not fully understood due to limited documentation from the 1200s to 1600s, the period during which Islamization is believed to have occurred. There are numerous theories about how Islam spread in region; however, the overwhelming evidence is strongly suggestive of a gradual transition of the local population from Buddhism, Hinduism and other indigenous religions to Islam starting in the thirteenth century facilitated by Sufi missionaries (such as Shah Jalal in Sylhet for example) and later by Mughal agricultural reforms centered around Sufi missions The factors facilitating conversion to Islam from Buddhism, Hinduism and indigenous religions, again is not fully understood. Lack of primary sources from that era have resulted in various hypotheses. Generally modern prevailing hypotheses about the early stages of Islamification of East Bengal focus on Sufi missionaries capitalizing on disaffected Buddhists and other indigenous groups following the initial conquest of the area by the Brahmin and Kshatriya dominated Sena Empire followed a few decades later by the arrival of Bakhtiyar Khalji of the Delhi Sultanate in the early 1200s and the later agrarian reforms of the Mughal Empire in the 1500s. Centuries prior to the advent of Islam into the region, Bengal was a major center of Buddhism on the Indian Subcontinent. The area was under the rule of the Buddhist Pala Empire for several centuries until its collapse and subsequent conquest by the Hindu Sena Empire in the 1170s. This was an era of significant Buddhist-Brahmin