From 1996-1999, 1605 was originally a house in Huntington Beach, CA (the address was 1605.. street confidential). 4 guys lived there (Sean, Marco, Lauren, and Duke), and some were noted musicians in the Local Scene. They made it an 'open-house' for frustrated musicians & social misfits in the Los Angeles / Orange County, CA area. It was a combination of a party house, recording studio (in garage), crash pad, community center, & insane asylum. The guys were cool, and had quite a social reputaion. Kottonmouth (then named "P-Town Ballers" aka "P.T.B.") recorded thier first demo there (Bump) when the band was just D-Loc, Richter, and Saint (yes, they were the original members of the group). In fact, the house is featured in the video "Suburban Life". 1605 threw wild parties, and some (then unknown) local OC bands such as: Kottonmouth Kings, Corporate Avenger, Lit, Orgy, Skinlab, etc; would all be regulars there.
The best thing about 1605 was the spirit of it: Make Music for music sake, never be a sellout, enjoy life while you're livin, and live how you want to live.
Time goes by, rentees move out, but the Kottonmouth Kings make the name "1605" famous in their songs. So after he moved out, one of the former housemates (Lauren) jumps on the idea to use it to make money on the name (since the name is famous, might as well suck out all the cash you can from it). He got some people together and marketed to the Suburban Noize fan base (cause they all heard of 1605). He made a company, (1605 Entertainment) and started selling t-shirts. He also started a record company (1605 records) and signed some local bands to give them more exposure (he has a website, a couple bands on the label, and merch to sell you). Now I'm not dissin 1605 entertainment, cause 95% of them are cool as hell, but I really feel that they have "sold out" cause they've lost sight of the vision and are too hard up on money. (Lauren would deny this, but you haven't seen what goes on behind closed doors over there).
Unfortunately, the actual 1605 died in 1999 when the guys moved out of the house. The spirit of it, however, lives in the hearts of Underground fans everywhere. So Kottonmouth still gives props to the old house, the memories, the original guys who lived there, and the original spirit that goes with the name "1605".

Credit for this goes to Dave over atThe Unofficial KottonMouth Kings Website