This may be linked to the concept in Voodoo of a crossroads ...and as such was exported to Haiti and New Orleans etc by the advent of the slave trade. As a style of worship best described by the reference as "Jesus in the Morning Voodoo in the Evening" perhaps there is no better example of two religions living side by side, thus, it is not surprising to see crosses in tribal artifacts.
On the other hand the cross is not unusual in other African cultures as seen by Tuareg jewelry and crosses therein linked to astrology.
The cross in weaving and hand knotted rugs off the silk road refers or means welcome ...As a candle light insignia often seen on Yurt Rug Door Hangings called Ketchli or Yatchlu.
Below illustrated cross concepts on Oriental Rugs and Tuareg Jewelry~