Chinese Buddhists adopted Indian cosmology based on Mount Sumeru and the Four Continents, which differed from native Chinese models. The four continents (Jambūdvīpa, Pūrvavideha, Avaragodānīya, and Uttarakuru) are positioned on a flat disc-shaped world. This was a type of flat earth cosmology that was documented in Abhidharma literature. The Buddhist canon does not mention a spherical earth, but Chinese monks were actually aware of an alternative cosmological model based on a spherical earth framework through the Jiuzhi li 九執曆 , a manual of Indian astronomy which was translated by Gautama Siddha in 718. This text introduced into Chinese the first instance of the concept of latitude (Skt. sva-deśa-akṣa). This sort of scientific theory based on a spherical earth model was already known by the mid-Tang. The Xiuyao jing 宿曜經 , compiled by Amoghavajra (705–774) in 759 with a subsequent revision in 764, not only adopts the cosmology outlined in Abhidharma texts, but also cites the Jiuzhi li. The issue at hand is why Amoghavajra and also the astronomer Yixing (673–727) never adopted cosmology based on a spherical earth. The present study will address these points.
