History
HISTORY

The evolution of ancient Osaka

Osaka's history has its origins in water.
In ancient Osaka, the coastline extended deep into the plains, with the Uemachi Plateau jutting out like a peninsula and an inland sea called Kawachi Bay to the east. During the Kofun period, Kawachi Bay became freshwater and turned into a lagoon, eventually transforming into Lake Kawachi. The Osaka Plain, formed by the accumulation of sediment from repeated flooding of the Yodo River and Yamato River, was prone to flooding. The Nihon Shoki contains many articles about large-scale flood control and water utilization projects, as well as civil engineering works to extend roads from north-south to east-west, suggesting that people sought land that was easy to live on and were improving the terrain.

During this period, Osaka was based as a port on the east side of the Uemachi Plateau, and cultures and technologies brought from various parts of the Seto Inland Sea, Kyushu, and even the continent spread throughout Japan. As ties with mainland China and the Korean Peninsula deepened, Naniwazu developed as the gateway to ancient Japan, serving as a place of entry from the continent and as a base for the travel of envoys, including those sent to Sui and Tang dynasties.

Emperor Kokutoku moved the capital here from Asuka with the start of the Taika Reforms and established Naniwa Palace here in 645. Urban construction progressed in Naniwa, which was Japan's leading international port.
During the Heian period, there was a port called Watanabe-no-tsu on the southern bank of Kitahama from Temmabashi, and it was a bustling place as the starting point for pilgrimages to Kumano, which were popular at the time.

Approximately 7000 to 6000 years ago
Sea levels rose 1 to 2 meters higher than current levels, and the water surface covered the Kawachi Plain, extending as far as the foot of Mt. Ikoma in the east, Yao in the south, and Takatsuki in the north.
A coastal state developed under the influence of the westerly winds, and a sandy beach stretched along the current Matsuyamachi-suji area.

Approximately 1800 to 1600 years ago
The sandbar of Tenma-Nagara extended far to the north, blocking the inflow of seawater into the Kawachi Plain (Kawachigata), and Kawachigata became a freshwater lake.

From the 5th century onwards
Due to flood control works carried out during the Nintoku period, the water area of Lake Kawachi decreased, and the branches of the Yamato River flowing into the lake formed deltas at the river mouth. These then became marshes, grasslands, and embankments, and the Kawachi lowlands then began to turn into land.

[Source] Osaka Brand Resources Report (Osaka Brand Committee, 2006)
[References] "Water City" Osaka Story (Hashizume Shinya, 2011)