Short answers, pulled from the story.
The Heian period began in the year 794 when Emperor Kammu moved the capital from Nara to Heian-kyō. This decision was made to escape the political and religious influence of Buddhist temples in the old capital of Nara.
The Fujiwara clan held real power during the Heian period by establishing a system of regency that allowed them to rule as hereditary dictators. By the year 858, the Fujiwara had effectively bypassed the emperor's authority through marriage alliances and administrative maneuvering.
The Heian period was defined by the introduction of the kana syllabaries and the creation of vernacular literature such as The Tale of Genji and The Pillow Book. Murasaki Shikibu wrote The Tale of Genji around the year 1000, and Sei Shōnagon wrote The Pillow Book, both reflecting the court's aesthetic values.
The Fujiwara clan's dominance began to crumble by the mid-11th century, giving way to the cloistered emperor system. Emperor Shirakawa abdicated in the year 1087 to rule from behind the scenes as a Buddhist monk, bypassing the Fujiwara regents.
The Heian period ended in the year 1185 following the Genpei War, which began in the year 1180. The war concluded with the defeat of the Taira clan at the Battle of Dan-no-ura and the rise of the Minamoto clan under Minamoto no Yoritomo.