Odd WWI (?) Holster...
 

...on e-Bay :

http://cgi.ebay.com/RARE-WWI-GERMAN-...QQcmdZViewItem

That looks to be made of pressed paper...or some other material and appears to have been cut for fast draw.

This appears to be of Bulgarian origin. The cut down would be normal for these holsters and not a GI cutaway. It is possible this holster is not a Luger holster. The magazine pouch does not have the cut out for the magazine pull on a Luger mag.
From the pretty good photo's I think it is all leather. On many period leather items, particularly small pieces, you can see a similar impression on the back. This is formed when the leather is fed into a leather splitter to make the leather thinner. The rollers on the machine that cuts the leather, splits it to a thinner thickness, has to grab one side in order to push it into the cutter blade. I suspect this is the pattern on the surface leather made by the roller. Normally this is found on the suede side of the leather but this hide may have been mistakenly put into the splitter upside down. Jerry Burney

It's a hide from a rare "Bulgarian Knurled Bovine". Very similar to a "Nauga".

Ron, I've seen some pretty fancy things made from the hide of those Naugas. It apparently is fairly easy to dye different colors too. I think that they were native to Sumatra though, but some may have been found in Bulgaria also.

http://www.nauga.com/history.html

I agree that the pattern is similar to the Bulgarian PO8 holster, but the width of the bottom is way too wide for a PO8. I think that rather this may be for a M1903 FN pistol in 9mmBL. which was popular with the central Europeans (Russian, Serbia, Latvia, etc). TH

A nice closeup photo of the detail of the mouth of the magazine pouch will give you a good idea as to what type of pistol the holster was intended for.

Saving these photos before they disappear from e-Bay :

http://forum.lugerforum.com/lfupload/odd_one_1.jpg
http://forum.lugerforum.com/lfupload/odd_one_2.jpg
http://forum.lugerforum.com/lfupload/odd_one_3.jpg
http://forum.lugerforum.com/lfupload/odd_one_4.jpg
http://forum.lugerforum.com/lfupload/odd_one_5.jpg
http://forum.lugerforum.com/lfupload/odd_one_6.jpg