Wafidiyya' was the term given to Turks and Mongols who exchanged military service to the Mamluk dynasty of Egypt in return for asylum.
Origins
After the Mongol invasion, of the mid east, a good number of displaced Turkish tribes fled to the Syiran border of the Mamluk dynasty of Egypt, there they were granted lands in exchange for military service.
Later on, their ranks were further bolstered by defecting Mongol tribes from the Ilkhanate.
Although they were highly effective nomadic horsemen, the Mamluk dynasty generally did not fully trust these troops due to their often being related to enemies on the other side of the border.
References
Wafidiyya Wikipedia(Text) CC BY-SA