Stormborn
Explorer
Perhaps the Neogi didn't travel through normal space at all, but used planar conjunction to bring their ships to Eberron. This could either mean that the Neogi originated on the other plane, or simple use it as a vehicle to raid other worlds and in fact originate from the same solar system as Eberron itself. As someone else mentioned, they could have been doing this for millenia, waiting for the right conjunction between there world and Eberron to open a window, perhaps one that is in a low stationary orbit above Khorvaire to come and raid before disappearing again. Thus it would seem as if they are arriving from space and returnign to it. This conjunction, however, could last longer than the others - and if their civilization is dying out they may have come with more than just a raiding party and are intent on full conquest and colonization of Eberron.