On which alternate world is Warlords of Draenor set?

Warlords of Draenor is set on an alternate version of Draenor. This is the orc homeworld as it existed before the catastrophic events that transformed the original world into Outland.

The story begins after Garrosh Hellscream escapes custody and travels 35 years into Draenor’s past with the help of the bronze dragon Kairozdormu. Garrosh prevents his father, Grommash Hellscream, from drinking the blood of Mannoroth. That change creates an alternate timeline in which the orc clans unite as the Iron Horde instead of becoming the Horde seen in Warcraft’s original history.

Azeroth is the heroes’ homeworld and the main setting of much of World of Warcraft, but it is not the alternate world named in this question. Outland is the shattered remnant of the original Draenor, while Argus is a separate world associated with the draenei and the Burning Legion. Warlords of Draenor deliberately revisits Draenor before its destruction.