Why is ancient calligraphy in China arranged vertically from right to left?

Write on bamboo slips with a brush, because it is usually written by the right hand, piece by piece. After a roll of bamboo rolls is opened, the rolled end is placed on the left and the unfolded end is placed on the right, so ancient Chinese characters are written from right to left. The present writing method was introduced from the west. Westerners write with quill pens, horizontally and from left to right, so as not to get wet ink dirty.