The early Dutch explorer Maarten Gerritsz Vries described the chashi he encountered in eastern Hokkaidō in 1643: These forts were made as follows: on the mountain on which they were placed was a small road steep to climb, and round on the four sides palisades were placed of the height … of 1½ man's length; within this stood two or three houses. There were large fir doors in the palisades with strong clamps; when they were closed, two stout bars were passed through the clamps and thus fastened to them. At the two corners of these … palisades, a high scaffolding is made of fir planks, for a lookout.