Precise regulations were published regarding the size of the postcards, and the format.
During this earliest period for picture postcards, the only information allowed on the back of the postcard was the addresses of the sender and and the recipient.
The back is reserved for addresses, and after 1907, for addresses and messages. Before this time, there were postcards, but due to postal regulations, it was not possible for companies to produce picture postcards until 1900.
The back of the card lacks a dividing line to separate the message and the address.
If you work with Japanese picture postcards as historical source material, you have probably noticed that most surviving cards lack postmarks and other temporal indicators.
This post provides a guide to estimating the age of these revealing artifacts, based on printing conventions that conformed to international and Japanese postal regulations.
This post also provides several examples and explanations of Japanese postmarks.
This chart by Urakawa Kazuya provides the basic method scholars use to subdivide Japanese picture postcards into four periods: Period I. 1/3 divided back: March 1907-March 1918 Period III.
“Kindai Nihonjin no Higashi Ajia, Nan’yō shotō e no ‘manazashi’: ehagaki no rekishiteki kachi no “ibunka” hyōshō” [The Japanese “Gaze” on the Peoples of East Asia and Micronesia: Archives Importance and the Other Race Representation, in the Japanese Picture Postcards]. One side of the postcard, the front, is dominated by a photograph, design, painting, drawing, or image.
Here are some more examples of undivided back cards from Period I: Some undivided back cards are military mail from the 1930s and 1940s.
It should be clear from the type of cardstock, imagery, and other clues that such cards are not from Period I: On March 27th, 1907, new postal regulations made it possible to use 1/3 of the back of a picture postcard for written messages.
Both countries were nominally sovereign and yet were governed by Japanese military and civilian officials.
Thus, it is not surprising to find that each nation, no matter how “fake” in retrospect, possessed distinctive flags, postage stamps, currency, and postal regulations.
1/3 divided back: March 28, 1907-February 28, 1918 Period III.