Overlord's Guard

Overlord's Guards are Horde soldiers located in Razor Hill and the Dranosh'ar Blockade in Durotar during the last stage of the War Campaign.

Speculation
Due to the note above (being unable to have previously invaded Orgrimmar), the facts that they use regular orc voice instead of the Draenor one, and that Overlord Geya'rah's sided with Sylvanas and remained in Orgrimmar, these Mag'har orcs may come from Outland's group.