Actually, the eras of Engi and Tenryaku fell upon the transitional period to the dynasty state from the Ritsuryo system (a system of centralized government based on the ritsuryo code) and the period when various reforms were carried out and these reforms were supported by not the direct rule by emperors but Sekkan governments which had been gradually formed.
実際には、延喜・天暦期は律令制体制から王朝国家体制へ移行する過渡期に当たっており、様々な改革が展開した時期であり、それらの改革は天皇親政というよりも、徐々に形成しつつあった摂関政治によって支えられていた。