There was a case in which earthware with a pattern engraved on it which could be pictographic was found; however, there is not enough regularity to call it a character due to the lack of other excavated examples.
絵文字とも思われる模様が刻まれた土器が発見された事例はあるが、発掘例も少ないため、文字と呼べるだけの規則性は見受けられないとされている。