The Salt Road: Supplying the Capital with Wakasa Salt
Overview
In the eighth century, certain areas along Wakasa Bay were important producers of salt, which has been essential for the seasoning and preservation of food for thousands of years. Historical records and archaeological findings indicate that seawater from the bay was used to produce salt through a combination of concentrating, boiling, and baking. At that time, taxes were paid in goods instead of money, and salt made in Wakasa was routinely shipped to the capital in Heijokyo (present-day Nara) as payment.
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Salt Production
Japan does not have rock salt deposits and is too humid to produce sea salt by evaporation alone, so for centuries the process involved using furnaces to boil seawater down to crystallized salt. Seawater was first poured over dried seaweed or seaweed ash to make a concentrate. Then it was boiled down in large earthenware pots to crystallize the salt. Finally, the resulting coarse salt was baked in clay pots, which separated bitter compounds and shaped the final product for convenient preservation and transportation.
Several salt production sites were discovered in the Wakasa region, including Okozu, an ancient state-run site that once operated near the coast in present-day Obama. Excavations revealed fragments of earthenware and the locations of several furnaces, and the area was designated a National Historic Site.
Supplying Salt to the Capital
Starting in the mid-seventh century, Japan introduced many legal reforms and adopted an official taxation system. One type of individual tax, called cho, had to be paid in goods other than rice (the staple at that time), and people of the Wakasa region paid much of their cho taxes in the form of salt. Multiple wooden tablets that were used as shipping tags for Wakasa salt were discovered during excavations of the site of the Heijokyo capital. Designations on some of the tablets use specific honorific wording suggesting that the shipment contents may have been intended for the emperor and the court.
Exhibition Items
The tools and models displayed in this section illustrate the salt production process used in the Wakasa region in ancient times. The fragments of earthenware vessels were excavated from the Okozu, Ano Shiohama, and Soneda salt production sites in Obama and Wakasa. The figurines in the exhibit show the main steps of making salt by boiling down seawater, and an artist’s rendition presents the kind of basket that historians believe was used to transport blocks of salt to the capital.
