The area of Ōmi has been settled since at least the
Yayoi period, and the traces of several large settlements have been found. During the
Kofun period, the area appears to have been dominated by several powerful immigrant clans, most notably the
Wani clan, which was originally from
Baekje, a state in the southwestern Korean Peninsula. The names Ōmi and Lake Biwa do not appear in the
Kojiki, ''
Man'yōshū'' or other ancient documents. Ōmi initially had various names. Wooden tags in archaic Japanese from the ruins of
Asuka, Yamato, the
Yamato Kingship's capital on and off from 538-710, mention the , or variations thereof, including . The archaic name
Apapumi evolved into the
current Japanese form, . The name was fixed as
Old Japanese only after the enactment and enforcement of the
Taiho Code in 701 and the decree of 713, which stipulated that the names of the provinces defined under the
Ritsuryō system should be written using two auspicious
kanji. The Yamato state ruled briefly from this region. In the late
Asuka period (538-710),
Emperor Tenji () built
Ōmi Ōtsu Palace in what is now the city of
Ōtsu and ruled from it from 667 until 672. He issued the first legal code, the
Ōmi Code, while ruling from the Ōmi Ōtsu Palace. After his death, the
Jinshin War broke out among his fourteen children, one of the largest conflicts in Japanese history. Ōmi was the site of several battles, and afterwards, the capital returned to Asuka. In the subsequent
Nara period, during the reign of
Emperor Shōmu (September 22, 701 – June 4, 756), the new
Ritsuryō system established a
kokufu (provincial capital) at
Ōmi Kokuchō in Ōtsu, near the ruins of the former Ōmi Ōtsu Palace. He also established a
provincial temple there. In 740, Emperor Shōmu built a personal residence, called
Rakumura, in what is now
Kōka, Shiga. He declared it the new capital in 745 and renamed it
Shigaraki Palace, but abandoned it the same year due to expenses.
Takebe taisha, enshrining
Yamato Takeru and his relics and
Ōkuninushi, was designated as the
ichinomiya (chief shrine) for the province. During the
Heian period (794-1195), the proximity of Ōmi to the capital at
Heian-kyō, its location on the
Tōkaidō and
Nakasendō highways connecting the capital with eastern Japan, and the main route from the capital to the
Sea of Japan, all gave the province great strategic importance. With the spread of
Buddhism in Japan,
Saichō founded the great
Tendai monastery of
Enryaku-ji in 788 on
Mount Hiei in Ōmi. From the late Heian into the
Kamakura period, the
Sasaki clan controlled the post of
shugo (military governor) of Ōmi Province, and two
cadet branches, the
Rokkaku and
Kyōgoku, dominated the province into the
Muromachi period. In the tumultuous
Sengoku period, internal struggles weakened both clans. Northern Ōmi became a battleground between the
Azai and
Asakura clans. In the south, the Rokkaku were supported by the
Kōka ikki, whose
shinobi operatives were infamous. In the late 1560s and early 1570s,
Oda Nobunaga invaded from the east, defeating the Azai, Asakura, Rokkaku, Kōka, and finally, in 1573, the
Ashikaga shogunate itself. Nobunaga built
Azuchi Castle near the southwestern side of Lake Biwa in Ōmi, from which he planned to rule all of Japan and beyond. After
Nobunaga was assassinated at Honnō-ji on 21 June 1582,
Toyotomi Hideyoshi awarded much of the province to
Ishida Mitsunari. Mitsunari would later be
Tokugawa Ieyasu's archrival at the
Battle of Sekigahara on October 21, 1600. After the establishment of the
Tokugawa shogunate in 1603, much of the province was divided into several
feudal domains, the largest of which was
Hikone Domain, ruled by the
Ii clan. Ōmi continued to serve as a transportation conduit, with five of the
53 Stations of the Tōkaidō and eight of the
69 Stations of the Nakasendō. Following the
Meiji Restoration, on November 22, 1871, Ōtsu Prefecture and Nagahama Prefecture were created from former
tenryō and
hatamoto territories within the province, and each former domain formed its own prefecture. These were merged on January 19, 1872 to form Shiga Prefecture. From August 21, 1876 to February 7, 1881, the Reinan region of
Fukui Prefecture (west of
Tsuruga, Fukui) was part of Shiga Prefecture, thus giving it a shoreline on the
Sea of Japan. Local inhabitants strongly opposed the merger, and it was withdrawn. ==Historical districts==