Board Thread:Suggestions forum/@comment-25604636-20160119130418/@comment-26350183-20160119234733

As far as canon goes, Morgul Knights are not canon in any respect. The term comes from some games, not any of Tolkien's work. However, Mordor is known to steal horses from Rohan, always taking the black ones. It doesn't mention if these were for the Nazgul exclusively, or for use in general. That's just a long way for me to say "While It's not canon, It's certainly not impossible."

As far as the question of Uruks go, It's really funny to see several people who have the wrong idea going after eachother for having a different wrong idea. Uruks are orcs. In Tolkien's writings people seem to have used the term "Uruk" to describe larger, more evil orcs. And yes, there were Uruks everywhere there were Orcs. Because, y'know, the same thing and all.

Saruman's Uruks are different, though. There's speculation from Treebeard that they may have been mixed with the Goblin-men Saruman has in his employ, or twisted with dark magic. But it probably had to do more with selective breeding. Maybe a combination.