Trịnh Tráng
In February 1631, Cardim was sent to Tonkin along with Miguel Matsuda and Pedro Kasui (two Japanese missionaries who were later martyred in Japan), where they were received with honor by King Trịnh Tráng. Learning of the existence of the Kingdom of Lan Xang, Cardim wanted to go to explore the possibility of establishing a mission there. However, the King of Ayutthaya would not allow Cardim to enter Lan Xang from Ayutthaya. Cardim later tried to enter through Tonkin, but fell seriously ill and was forced to return to Macau. In Macau, Cardim served as rector of St. Paul's College from August 1632 to May 1636.