There were a number of companies that sold airsoft guns. Most of them are in Japan. The only one that I'm aware of in the US is Daisy, and they've done more than enough to earn my ire.
The two that someone in the states is most likely to be be familiar with are Modelgun Corp and Marukoshi.
Modelgun Corp always produced the most advanced airsoft guns that I saw here in the states. They started freon systems. They were the first to put the gas cylinder in a removable magazine with the pellets. They made the first full-auto airsoft gun that I ever saw. And their guns were consistantly accurate.
I dunno if MGC is still in business. I hope so. Maybe they've got a web page. Maybe I should actually look.