Before the Horde was a bunch of outcasts living in the world that is intent on killing them while the Alliance consisted of entire nations with dozens of cities and large outposts. Now:
Orcs- Ogrimmar
Forsaken- Refugees
Tauren- Thunder Bluff
Trolls- Echo Isles
Blood elves- Silvermoon
Goblins- Bligewater Harbor
Nightborne- Suramar
Zandalari- Zandalar
High mountain- Thunder Totem
Humans- Stormwind
Night elves- Refugees
Gnomes- Refugees
Worgen- Refugees
Void elves- Refugees (I wouldn't call a void infested rock with no settlements as a home)
Draenei- Exodar
Dark Irons- Shadowforge
Kul Tiran- Boralus
Dwarves- Ironforge
Horde 1/9 refugees
Alliance 4/9 refugees
Besides the capitals, the amount of outposts and smaller towns that the Alliance lost is absurd while Horde lost Taurajo, Brill and umm...
Almost half of the Alliance races are refugees, 3 of them at the hands of the present Horde. Now the Alliance is in the world that is intent on killing them.