The first fully documented use of the Grimsel Pass dates back to the 14th century, although it has been suggested that the pass was used in Roman times and also, in 1211, by troops of Berthold V, Duke of Zähringen. In 1397, the Landschaften of Pomat, Goms and Hasli, and the cities of Interlaken, Thun and Bern, signed an agreement in which it was agreed to provide for free and secure trade by the mule track over the Grimsel.