Sixteenth century men's and women's qabai often appear in paintings as having a decorative area around the neck and shoulders. These are called "cloud collars" and they were derived from Mongol clothing. In paintings some cloud collars are the same color as the garments on which they appear while others are a different color. I have wondered whether they were sewn directly onto the garments or if they were separate items of clothing.
Unfortunately i know of only one surviving cloud collar, currently in a Russian museum, and it has been very much altered from its original state. Apparently the collar was cut off a garment and in the 18th century the original red silk base fabric was entirely stitched over with a yellow thread onto a backing of Russian linen. This would suggest that the cloud collars were originallly sewn onto garments, not separate items.
I would assume that when they were a different color, they were embroidered separately before being sewn onto the garment. If the same color they might have been embroidered separately and sewn on, as that would be easier than embroidering onto the full garment.
Interestingly, several designs for cloud collars painted in illuminators ateliers have survived.