Here's the draenei's story up until the beginning of WoW:The Burning Crusade.
Their homeworld is Argus, where they were known as the Eredar until Sargeras came and corrupted Archimonde and Kil'Jaeden. Velen fled with the Naaru within Oshu'gun which crashed into Draenor.
The orcs and the draenei ("exiled ones") became friends until Kil'Jaeden arrived years later and corrupted nearly all the orc clans. The Draenei retreated from the Temple of Karabor (Black Temple), Shattrath City, and many of their other abodes to strongholds of the naaru like Tempest Keep or to hidden lands like Zangarmarsh. Many draenei devolved into the broken and the lost ones. Decades passed until Ner'zhul's portals ripped Draenor apart creating Outland.
The Ashtongue (Akama's draenei) remained hidden until the day Magtheridon arrived. This upstart pit lord rallied the remaining orcs and summoned countless scores of demons through the dimensional gates across Outland. Akama and his broken fought for months until help arrived in the form of the Betrayer, Illidan. Illidan's forces and Akama's draenei destroyed Magtheridon's forces and invaded the Black Temple imprisoning him within the Hellfire Citadel.
About 5 years after Illidan's coming, blood elves loyal to the treacherous Kael'thas raided Tempest Keep, imprisoning the lone naaru within and taking over the entire keep except for the Exodar. The draenei aboard the Exodar soon crashed into Azeroth's Azuremyst Isles. Soon after their arrival an Alliance fleet welcomed them wishing for peace and help against the draenei's old foes, the orcs.
