Jean Baptiste De Regis, a French geographer, born at Istres in Provence about 1665, died in China about 1737. He was a Jesuit, and was sent to China as a missionary about 1700. His scientific attainments gained him a place at court and the favor of the emperor Hang-he, who in 1707 placed him at the head of a commission of Jesuits for making a survey and drawing up a map of the Chinese empire. Beginning with the great wall and the adjacent provinces, he completed a 15 ft. map of them, which he presented to Hang-he in January, 1709. He then drew up maps of Mantchooria, Pecheli, and the region drained by the Black river (1710); in 1711-13 he surveyed and mapped Shantung, Honan, Nanking, Chekiang, and Fokien. The health of his companions failing, he accomplished alone the survey of Yunnan, and, assisted by Father Fridelli, he finished the maps of Kweichow and How-kwang (now Hupeh and Hunan). While thus completing surveys of extraordinary magnitude, he also wrote a full history of his labors, which is in part condensed in the preface to Du Halde's Description de la Chine (4 vols. fol., Paris, 1735). Of the copious memoirs which he composed on the topography of the various provinces, their resources, and the manners and customs of the inhabitants, only two fragments are published by Duhalde in vol. iv. of his Description, one relating to Corea and the Coreans, and the other on Thibet and the hierarchy of the lamas.
His knowledge of Chinese enabled him to translate into Latin the Yih-king, with copious notes and dissertations (edited by Julius Mohl, 2 vols., Stuttgart and Tubingen, 1834), the manuscript of which is in the national library of Paris. His labors were interrupted in 1724, when the emperor Yung-ching proscribed the Christian religion.