I was amazed to learn that the Japanese people didn't use a writing system until the 4th century, and even then it was just Chinese. Not an adaptation of Chine

I was amazed to learn that the Japanese people didn't use a writing system until the 4th century, and even then it was just Chinese. Not an adaptation of Chinese characters, which came later, but the Chinese language. Japan had agricultural residents since the 4th century BCE. To go 800 years without writing, despite depending on long-term planning and trading to survive, is incomprehensible to me.