the of 1868. Heian period During the Heian period Buddhism became even more infused with Japanese elements: It met and assimilated local beliefs concerning ghosts and spirits (the so-called onrei and mitama), developing traits close to magic and sorcery which allowed it to penetrate a wide spectrum of social classes. Its merging with indigenous religious belief was then accelerated by the systematization of the syncretism of Buddhism and local religious beliefs (see the article on the honji suijaku theory, which claimed that Japanese kami were simply Buddhist gods under a different name). It was in this kind of environment that Fujiwara no Michinaga and retired Emperor Shirakawa competed in erecting new temples, in the process giving birth to the Jōdo-kyō architecture and the new wayō architectural style. The early Heian period (9th–10th century) saw an evolution of styles based on the esoteric sects Tendai and Shingon. These two sects followed faithfully the Nanto Rokushū architectonic tradition in the plains, but in mountainous areas developed an original style. This development was facilitated by the syncretic fusion of foreign Buddhism with local mountain worship cults. Called to distinguish it from imported Chinese styles, it was characterized by simplicity, refrain from ornamentation, use of natural timber and in general plain materials. Structurally, it was distinguished by: a main hall divided in two parts; an outer area for novices and an inner area for initiates; a hip-and-gable roof covering both areas; a raised wooden floor instead of the tile or stone floors of earlier temples; extended eaves to cover the front steps; shingles or bark rather than tile roofing; and a disposition of the garan adapting to the natural environment, and not following the traditional symmetrical layouts. The tahōtō, a two-storied tower with some resemblance to Indian stupas, was also introduced by these sects during this period. According to an ancient Buddhist prophecy, the world would enter a dark period called Mappō in 1051. During this period the Tendai sect believed that enlightenment was possible only through the veneration of Amida Buddha. Consequently, many so-called Paradise (or Amida) Halls—such as the Phoenix Hall at Byōdō-in (1053), the Main Hall of Jōruri-ji (1157) and the Golden Hall at Chūson-ji (1124)—were built by the Imperial Family or members of the aristocracy to recreate the western paradise of Amida on earth. Amida Halls that enshrined the nine statues of Amida were popular during the 12th century (late