In the 17th century, the idea of a spherical Earth spread in China due to the influence of the Jesuits, who held high positions as astronomers at the imperial court. Matteo Ricci, in collaboration with Chinese cartographers and translator Li Zhizao, published the "Kunyu Wanguo Quantu" in 1602, the first Chinese world map based on European discoveries. The astronomical and geographical treatise "Gezhicao" () written in 1648 by Xiong Mingyu () explained that the Earth was spherical, not flat or square, and could be circumnavigated.