Here is a photo of the Mecca style Jambiya reffered to by Steve.
The handle is silver and the pommel is supposedly a presentation of the Kaaba mosque in Mecca. I have however seen similar handles on Yemeni and Hadramout daggers as well (see my comment on the origin of styles below).
More Yemeni Jambiya daggers from our private collection below:
#1) Rhino horn handle with silver fittings
#2) Supposedly Amber handle (need to confirm it)
#3) Whole silver handle, silver scabbard.
#4) Rhino horn handle with silver fittings, silver scabbard.
#5) Rhino horn handle with pierced silver fittings.
#6) Rhino horn handle with silver fittings and colored stone also on the scabbard
#7) Cow horn with silver nails
Regarding # 5 and 7, the size, scabbard style and pierced fittings suggest an Indian origin. May be made in India for export to Arabia or for the use of local wealthy Arab.
To the origin of styles:
The attempt to identify and typify the styles of handle and scabbard to a certain area or origin is a great challenge and I hope someone will do it. Yet I am afraid that styles has been migrated during the last 200 years all over the peninsula, changed blades and scabbards so what we see today is a mix of all styles all over. Best of luck to whoever will challenge it.