If the AEG has the Kalashnikov brand attached to it it's a Cybergun product.
Cybergun gets it's AK's manufactured mainly by Cyma and to a lesser amount, Jing Gong.
King Arms, ICS and G & G among others (Inokatsu?) also have partnerships with Cybergun.
D-Boys also might be in the mix but for example the Cybergun "Kalashnikov" AKM is the faux wood version that Cyma makes and not all black version that D-Boys offers. There are quite a few Kalashnikov EBB's as well. Cyma and Jing Gong offer up quite a few EBB AK's.
To answer your question the OEM is most likely Cyma.
Originally Posted by Aper
Anyways, it's not my problem. Enjoy your overpriced shaving acessories.