While a small number of ink-inscribed tablets had been carefully preserved for centuries in imperial repositories, the vast majority was not discovered until the second half of the 20th century. Since then, excavations of sites mostly related to local or central government facilities, elite residences, and temples have yielded hundreds of thousands of inscribed tablets (mokkan) or wood shavings (kezurikuzu) that were created when the original surface of a tablet was scraped off with a knife to create room for a new inscription.

Because these tablets can be studied in two ways, either as excavated artifacts or as written sources, they bridge the gap between the historical records and the archaeological sources, and add an enormous and invaluable amount of depth and detail to both.

Unlike the written sources copied and transmitted for centuries in paper form, the texts on the tablets contain details concerning daily life that were deemed too trivial to be worthy of inclusion in the court chronicles and temple histories. They also provide firsthand information that was not edited to suit certain goals or narratives. As a result, our understanding of various aspects of government, economy, and society in ancient Japan has changed and we have been allowed glimpses of the practical execution of government regulations and of daily life.

As archaeological material, mokkan have also contributed to a better understanding of other remains as some of the tablets allow for precise dating and identification. The study of the types of wood used for the tablets and the way the tablets were manufactured also contributes to a better understanding of communication and transportation networks in ancient Japan.

However, although the tablets provide a vast amount of detailed data, it can be difficult to make generalizations based on the information provided because the inscriptions are fairly short and there is often no follow-up to the initial message. It is also possible that the discovery of new tablets will stand today’s accepted truth on its head.