How rare are these horn tipped sudanese spears
 

Ive recently picked these large Sudanese spears up , the heads are made from horn , they are quite tall measuring about 8 feet tall with the horn tip measures 50cm , I cant seem to find out much about them , is it because they are rare ? im not sure

I looked at horn headed Sudanese spear heads on the Web and came up with a few variants . Ashok arts places a worthy write up here Viz;
QUOTE " Wonderful Rare Sudanese Dinka Shilluk Mandari Horn Spear with ostrich plumage.
A rare and most interesting spear from tribal Sudan. The blade formed from an entire horn from an antelope probably the gemsbok or oryx as were traditionally used. This spear could be from one of several tribes who used similar forms including the Dinka, Nuer, Shilluk and Mandari. The horn has been fixed to the wooden spear shaft using seamless hide from the tail made wet and shrunk solidly onto the join to make an extremely solid and strong binding. Similar techniques can be found on spears from Southern Africa such as Zulu and Shona weapons. The spear shaft here is decorated by rings of Ostrich feather to the top and bottom, the very end is bound with a strip of snake or lizard skin. There are several spears of this type in the Pitt Rivers Collection in Oxford, collected and donated by various owners during the early 20th century, some of which were purchased in Omdurman. This spear likely dates to a similar period circa 1900. One side of the horn has an old shrinkage split, and the feather decoration is worn and loose, this is a rare artefact and a wonderful display piece." Unquote

Thanks for your reply and posted write up , its good to see some information on them , ive bought and sold lots of African spears in the past but this is the first time ive encountered and owned these type , quite unusual for sure

This is outstanding research on this very unusual spear! I have been pretty familiar with lots of Sudanese stuff, but quite honestly have never seen one of these horn types. I thought perhaps a tribal form from other regions as was known during the Mahdiyya with other tribal factions converging in Omdurman as they often brought their own weapon forms.
Very much appreciated to add to notes, and 'head knocker' thanks for posting it!