The Yamato period (300 - 710) had an organized ruler, civilozation, etc. However, only in Nara period (710 - 794), which existed along with the Tang dynasty of China, a Japanese script and language were defined by 万葉仮名 (Manyogana). These where phonetic Chinese characters, forming an "alphabet" and a proto-script for Hiragana and Katakana. So my question is, what script or language did they use during the Yamato period? I can not imagine Chinese, but maby an early Japanese using Chinese characters?