In summary, Velen have been planet hopping for centuries, leading Kil'jaeden with a tour on the universe, and creating the conquering of at least some worlds from the Legion. However, Velen and his individuals were always capable to escape.
See, Kil'jaeden held a tremendous grudge against Velen for not joing the Legion. Archimonde not really. Searching for the draenei was Kil'jaeden's hobby.
When he finally tracked these to cheap runescape accounts , after several failed invasion attempts on other worlds, he decided to try a different means for an alteration. Although instead corrupt the native inhabitants of the world and employ them as his pawns.
Kil'jaeden seemed to Ner'zhul, the High Shaman (closest thing to some racial leader that the orcish clans had during the time), and started to use various illusions to convince him the secretive draenei were plotting to eradicate the orcs. This included both appearing as his orcish ancestors, so when a lovely supreme being.
However, when Ner'zhul realized he had been manipulated, Gul'dan had already supplanted him as Kil'jaeden's apprentice and High Shaman.