The item is a vintage (but could be antique) genuine leather watchstrap. These styles of items were generally known as “shipwreck” watchstraps.
To read further about these watchstraps, you can follow this link:
http://www.vintage-watches-collection.com/watch/shipwreck-straps/shipwreck-leather-straps-for-early-wristwatches/
The watchstrap is not marked or stamped.
In very good vintage condition with no damages noted.
Length: 22 cm, Width: 4.8 cm