Why is Osaka called Osaka (big slope) with even no slope?

An American man who lived near Osaka asked me: "Why is Osaka called Osaka (big slope) even though there is no big slope?" This question is difficult for me, even though I've lived near Osaka for over 50 years.

Osaka is a big slope

Look at this picture.
This is a current topographical map of Osaka. Red means high elevation (114 metres from the sea), yellow is moderately high, blue means sea level.
A ; Umeda area, which is the most densely populated area in Osaka
B ; Osaka Castle

From this picture, you can see that Osaka is a big slope, which is from Umeda or the seaside area to Osaka Castle. However, this big slope is so large and is beneath many tall buildings, therefore people have trouble to perceive that this area is a big slope.

quote from Geospatial Information Authority of Japan, addtional captions by Yoshiteru

FYI: The Osaka City official website explains the origin of the name of Osaka is not clear, however the oldest paper in which "Osaka" appeared was the letter written by the high buddhist priest "Ren-Nyo" in the 15th century. (He was also the establisher of the temple Ihiyama-honganji which was located in the same spot of Osaka castle)

Geography teaches us about history

Osaka castle (B)

Osaka castle was the most important spot in Osaka among the leaders in the Age of Civil Wars (around the 16th century). You can realise the reason why by looking at the picture above. The location of the castle is easy for both offence and defence during a conflict.

Daisen-kofun (C)

Daisen-kofun is the largest tomb in Japan (the length is 840 metres). The era the tomb was constructed was the 5th century. That means the pale blue area of the above picture was the sea at the time. It shows the reason for the location of the tomb. The leaders at that time had intended to show this big tomb as the power of Japan to people on the ships who were from Korea or China.

High elevation spots (D and E)

D and E are the unique points in the picture. What are they?Both spots are manmade mountains.

D is Tsurumi-ryokuchi park. Now it is a popular green park, also the site of the International Garden and Greenery Exposition in 1990. Before that, however, the spot was a large accumulation of the rubbish. The park is 39 metres from sea level, the highest spot in the entire Osaka city area, constructed by old rubbish.

E is chishima park, also the manmade mountains. It was constructed with the soil from subway construction in 1970.



Geographical features teach us both the origin of the name of the city and the history, even though native people don't know.