His primary research interest is modern Southeast Asia, and he teaches courses in Modern Asian History and Southeast Asian History from the Eighteenth Century. His first book, Secret Trades, Porous Borders: Smuggling and States along a Southeast Asian Frontier, 1865-1915 (Yale University Press, 2005), analyzed the history of smuggling in the region. In 2005, he received the competitive Smithsonian/CAORC Grant to travel to Yemen and Insular Southeast Asia for three months during the summer of 2006 and continue research on the history of the Hajj from South East Asia to Mecca. He is currently working on a book called The Longest Journey: Southeast Asians and the Pilgrimage to Mecca.