The arrival of the Portuguese explorers in the late 15th century checked the then well-established and wealthy Muslim community's progress. As the Portuguese tried to establish monopoly in spice trade, bitter naval battles with the zamorin ruler of Calicut became a common sight. The Portuguese naval forces attacked and looted the Muslim dominated port towns in the Kerala. Ships containing trading goods were drowned, often along with the crew. This activities, in the long run, resulted in the Muslims losing control of the spice trade they had dominated for more than five hundred years. Historians note that in the post-Portuguese period, once-rich Muslim traders turned inland (southern interior Malabar) in search of alternative occupations to commerce.