Early Arab Muslims established commercial as well as religious contacts within the region before the conquest, mainly through the coastal regions as traders and primarily via the ports of Chittagong. Arab navigation in the region was the result of the Muslim reign over the Indus delta. The activities of the Muslims were expanded along the entire coast of South Asia including the coasts of Bengal. The religion of Islam entered the region in many different ways, the Muslim traders, the Turkic conquest and, the missionary activities of the Muslim Sufis. One of the authentications of the Arab traders present in the region was the writings of Arab geographers, found on the Meghna River located near Sandwip on the Bay of Bengal. This evidence suggests that the Arab traders had arrived along the Bengal coast long before the Turkic conquest. The Arab writers also knew about the kingdoms of Samrup and Rumi, the latter being identified with the empire of Dharmapal of the Pala Empire. The earliest mosque in South Asia is possibly in Lalmonirhat, built during or just after the Prophet Muhammad's lifetime.