Not sure how many Mamelukes were ethnic Russians or Ukrainians—those areas are far from Egypt. But Egypt, after the Mamelukes seized control, was one of the few countries to defeat the Mongols, at Ain Jalut in 1260. Afterwards, they eliminated the last of the Crusaders in the Middle East. Even after the Ottomans conquered Egypt as a result of the Battle of Cairo in 1517, they allowed the Mamelukes to run the country until 1811, when Egypt’s Ottoman ruler Muhammad Ali had them massacred.
The Mamelukes were the equivalent of the Janissaries, slaves imported specifically for military work. Most of them came from the area north of the Black and Caspian Seas.
But most were Circassians or Turks. Few if any were Slavs. The buyers wanted horse and bow nomads.