This map can be expanded, to some extent. You can see that it shows the current borders of the area, showing what is now southeast Poland, northeast Slovakia, northern Transcarpathian Oblast, southern L'viw Oblast, and western Ivano-Frankiwsk Oblast. You can see a second line to the right, showing the lowland areas which were sometimes called Boiko in the past, I will be using this map to show the approximate extent of the various costume regions.
The most distinctive part of this costume are the vests, which are made of dark wool, naturally colored, with white and red cord trim. The man's being shorter. White linen skirt and apron, embroidered near the hem and seam, and smocked at the waistband.
Womens' shirts are embroidered on the upper sleeve, shoulder inset, cuffs, collar, and have varying amounts of smocking. The front opening is mostly in the middle. Embroidery used includes cross stitch and nyzynka.
Across the border, in L'viw Oblast, southern Skole district, the costume is somewhat different, especially the vest used. This includes the villages of Volosianka and Tukhol'ka. The vest seems to be made of woven wool, and is embroidered in the floral style of the northeastern Boikos
The men in this region used to wear a shirt which was smocked front and back, and had embroidery on the collar, cuffs, and epaulets.
The second variant is where the Boiko costume was replaced wholesale by the Halychyna Town Costume. At this point I hesitate to call this a Boiko costume.