There are two Paleotethyan volcanic arcs in the Sichuan-Yunnan-Tibet border area: the west one named the North Lancangjiang Arc, which was of Early Permian and was related to eastward subduction of the Bitu Ocean (a major Paleotethyan oceanic basin), and the east one the Haitong-Xuzhong Arc, which was of Late Permian to Early Triassic, recording the westward subduction of the southern segment of Jinshajiang Ocean (a branch Paleotethyan oceanic basin). In this paper, petrochemical evidence to support their existence is discussed, providing temporal-spatial constraints for making the Paleotethysides clear. There are two Paleotethyan volcanic arcs in the Sichuan-Yunnan-Tibet border area: the west one named the North Lancangjiang Arc, which was of Early Permian and was related to eastward subduction of the Bitu Ocean (a major Paleotethyan oceanic basin), and the east one the Haitong-Xuzhong Arc, which was of Late Permian to Early Triassic, recording the westward subduction of the southern segment of Jinshajiang Ocean (a branch Paleotethyan oceanic basin). In this paper, petrochemical evidence to support their existence is discussed, providing temporal-spatial constraints for making the Paleotethysides clear.