In the early Heian period, the ninth century, Kukai, Saicho, and other Buddhist monks went to Tang (to China for study) one after another and brought the systematic Esoteric Buddhism to Japan.
平安時代初期の9世紀になると空海、最澄らの僧が相次いで入唐（中国・唐へ留学）し、日本へ系統的な密教を伝えた。