There were circumstances in which Emperor Koken favored the Buddhist monk Dokyo, and Dokyo, hoping for a little luck, even tried to become the emperor but was prevented from doing so by WAKE no Kiyomaro, and therefore one motivation for the transfer of the capital to Nagaoka-kyo and Heian-kyo was to eliminate the influence of Nara Buddhism, which wielded too much power under the protection of the court.
孝謙天皇が僧・道鏡を寵愛し、あわよくば道鏡が天皇にまでなろうとして和気清麻呂に阻止された経緯があり、朝廷の保護の下、力を持ちすぎた奈良仏教の影響を排除することが長岡京、平安京への遷都の一つの動機である。