[BobL]

If China was writing 5000 years ago, it would seem reasonable to assume some of that capability made it to Japan, long ago.

[SunkenCiv]

China was writing perhaps 3500 years ago, rather than 5000.

[SunkenCiv]

This link won’t work for me, has an outlandish claim (7000 BC writing in China) that I just must look at later:

https://www.cambridge.org/core/journals/antiquity/article/earliest-writing-sign-use-in-the-seventh-millennium-bc-at-jiahu-henan-province-china/6DDB3E0583ACB6896B3DBCAC143FA846