From which dynasty did foreign students come to China to study, take the imperial examination and serve in the imperial court?

During the Sui and Tang Dynasties, Koryo, Silla, Baekje (all on the Korean Peninsula), Japan, Lin Yi (now Vietnam), Nipolos (now Nepal), Guo Si (now Myanmar), Songkhla (now Thailand), Zhenla (now Cambodia), Sri Lanka Buddha died (now Sumatra, Indonesia) and Hu Ling (now Java, Indonesia). Silla and Japan have the largest number of international students, and there are not a few officials.