[ariel]

Ibrahiim,

Here is my version of your request:
IMHO, Bukharan ( not Afghani, as per Lebedinsky!) pseudoshashkas ( sorry for a totally inappropriate term, but for want of a better one...) derive their origin not from the shashkas of Russian invaders and subsequent occupants, but from Khybers or their earlier analogs. Here is the series of graded modifications: classical Khyber at the top, early Bukharan " shashka" in the middle ( straight blade, almost triangular geometry) and classical Bukharan "shashka" ( slightly curved blade, almost "hatchet" point). The last two swords are attributed to Bukhara ( more precisely Central Asia) partly by the characteristic feature of 5 rivets ( 2x1X2).

Jim,

In a little while a paper one of my Russian colleagues and I have written together will appear in a major arms history journal. It will be dealing with the origin of yataghan blades and a large part of it will be referring to tunkou, the heretofore forgotten or neglected element of Ottoman yataghans.
Just in brief, it is not an inherently Ottoman, but a Turkic element, tracing back to nomads, Seljuks and Mongols included. This is why we see it or its renditions on some Persian and Indo-Persian blades and even in some very early European iconographic sources.

And I completely agree with Ibrahiim's point: the eared pommel of Caucasian shashka likely stems from the same element of the Ottoman yataghans.