Some ports of Yoda River had gradually changed since ancient times. Through the study of the transportations process, I have made it clear that the function of P. Yoda was most important in the middle ages, and consider that the changes of the economic location by Historic-Geographical Research.
The welfare of P. Yodo can be divided into five stages as follows.
1) The transpartation of Yodo R. and the Locatian of “Yodo” in pre Nara Era [710∼784. A.D.]
2) The change of main road and the beginning of the P. Yodo in the first period of Heian Era [794∼907. A.D.]
3) The comparative consideration about the function of P. Yodo and P. Yamazaki[_??__??__??_]
4) The enlargement of P. Yodo's hinterland and change of P. Yamazaki's functions.
5) The divided process of P. Yodo's fuction. The centre point of problem lies in the function of P. Yodo and P. Yamazaki.
Two port competed to obtain the hinterland of Miyako Kyoto in the first period, but P. Yodo is more developed by the forwarding agents (Toimaru)[_??__??_]of Shoen[_??__??_].
With the advancement of the Shoen at P. Yodo consequently P. Yamazaki, P. Uji[_??__??__??_], P. Kizu[_??__??_]had been on the decline. Since P. Fushimi[_??__??_]had established (about A.D. 1594) and set up marine products market (Sakkoba)[_??__??__??_]in Osaka P. Yodo has gradually been declined.
