These Japanese women are beautifully dressed, from their parasols to kimonos to uncomfortable looking wooden sandals. However, the article of clothing that may not have caught your eye is the obi. An obi is a sash that's used to hold traditional kimonos closed. Originally a simple cord or braided rope, the obi evolved over time into a large piece of elaborate fabric. It would often be between 9-12 inches wide and over 12 feet long! Because the size of the fabric used for obis grew to be this big, it became inconvenient to tie in the front of the kimono. Starting in the 18th century, the obi began to be knotted in the back. However, tying an obi is not as simple as you may think. There are many ways to tie an obi, and each way can have special meaning. Unmarried women would often wear fancy, complicated knots, while married women typically wore simpler knots. Take a closer look at the picture to see what kinds of obi knots these ladies are wearing!